President Reagan beamed with self-congratulations last night, standing in the Blue Room of the White House, where the talk around him was of his surprise announcement that Assistant Secretary of State John H. Holdridge would be the new U.S. ambassador to Indonesia.

"We had decided in our minds, but we also had to find out from the country he was going to," the president said of the sequence of events leading to the announcement. "That we could not find out until today."

The president said that as far as he knew, his announcement, which came during the state dinner in honor of Indonesia's President Suharto, was a first. "It's a first for me," he said.

Reporters told the president about the White House briefing earlier in the day at which Holdridge was studiously vague on the question of who the Reagan administration was going to name ambassador to Indonesia. "You didn't get suspicious?" the president asked. "How come you all get suspicious when I hedge around?"

Across the room, President Suharto beamed, too.

"It's very good; I know him," he said of Holdridge. "It's a great honor for Indonesia to have someone appointed who is a highly experienced senior diplomat."

Suharto said that earlier in the day he and Reagan had discussed the Holdridge nomination for the post, which has been vacant for a year. He said he had known of only one other candidate, but declined to confirm that it was career diplomat Morton Abramowitz, whose rumored nomination sparked concern among the Indonesians. And what about Kent Crane, the Washington businessman thought to have been a leading candidate, if also a controversial one? Suharto smiled innocently. "I didn't know at all about that," he said.

As it turned out, both Holdridge and Crane were among the 120 black-tie guests at the dinner.

Pausing between dances with his wife, Holdridge kidded reporters about his performance at the White House briefing. "You don't let him the president hedge, but I got away with it."

He said the appointment had been in the works only since Saturday. And when did he accept? "The moment it was offered," he laughed. Looking at his wife, Martha, he added, "I had to discuss it with my chief of staff."

Holdridge, whose area of expertise at the State Department long has been East Asian and Pacific affairs, said it was "rather unique" to be named during a state dinner and that afterwards he spoke briefly with President Suharto about it.

"We've all been shaking hands with big smiles," Holdridge said.

His boss, Secretary of State George P. Shultz, called the nomination "A-plus -- Indonesia knows him and the president trusts him."

Vice President George Bush was ecstatic at the announcement, calling it "a marvelous tribute to Indonesia because he's a senior diplomat and so highly regarded. I served with him in China. I couldn't be more enthusiastic about it."

And from one who didn't get the nomination: "You didn't expect to see me here, did you?" laughed Kent Crane when he arrived.

"I never was a nominee, remember that, just someone on the list," said Crane. Of reports that he handled Suharto family investments, Crane, a consultant and international investment counselor, said, "I never did any business with any government in any country, so this has been an interesting experience." Of Holdridge, with whom he had worked at the National Security Council: "They got a good man."

But he didn't deny that he would have liked the job. "It's the best country in the world, a beautiful place. I speak the language; I worked there three years -- a baby diplomat, you know -- it was my first post in the foreign service."

Not the CIA, as was speculated around town when his name surfaced as a potential nominee?

"The foreign service," Crane repeated.

Some other old friends at the dinner were comedian Joey Adams and his wife, author Cindy Adams, who wrote the life story of Suharto's predecessor, former president Sukarno. He was ousted in 1967 and the Indonesian legislature named Suharto acting president. The following year he was formally elected to the post.

"Don't go heavy on Sukarno -- it's the wrong group," cautioned Cindy Adams.

"One thing I'm not going to do tonight is tell jokes about Sukarno," said her husband, who told of being sent to Indonesia as a "goodwill ambassador" by President Kennedy. "Sukarno was our great friend. So you can't make fun of him."

After a dinner of tenderloin of beef, souffle potatoes and Pear Williams Bombe, the Adamses had a brief chat with Suharto in the Blue Room in which they repeatedly praised Indonesia and expressed the hope that they could soon return. Suharto nodded with a smile.

Yet another Indonesian friend was golf pro Arnold Palmer, who said the fact that President Suharto is a golfer probably had something to do with his invitation to the dinner. He told of a golf course he expects to build in Bali.

"At the moment it's on hold, but we expect to see something happening very soon," said Palmer.

A Californian with strong ties to Indonesia as well as the Reagan administration was Stephen D. Bechtel Jr., chairman of the Bechtel Group Inc., the corporate alma mater of Secretary of State Shultz and Defense Secretary Caspar W. Weinberger, who was also there last night. Bechtel said his firm has three projects going on at the moment in Indonesia, two of them involving liquefied natural gas and the other the modernization of a refinery. He said he didn't make it to Washington too often because "I like San Francisco."

After the entertainment, a recital by mezzo-soprano Frederica Von Stade with pianist Martin Katz, Shultz and his wife Helena took a turn around the dance floor. Then Shultz took Nonie Bechtel Ramsay, daughter of his former boss, on another turn.

Actress Alexis Smith led the glamor contingent, which also included Gloria Vanderbilt being escorted by author and -- as the White House called him -- "cuisine expert" Craig Claiborne, and Washington socialites Ina Ginsburg and Wendy Morgan. From Bonner Springs, Kan., came Leroy Tombs, chairman of the National Association of Black Manufacturers and a longtime friend of Kansas Sen. Robert J. Dole (R). Speaking as co-chair of the Republican Black Council, Tombs said that "blacks have been with him Reagan all along. Blacks have found what's basically good for America is good for them."

Not far behind was Treasury Secretary Donald T. Regan, who turned thumbs down when asked about the downturn in stock prices yesterday. "Profit-taking," he explained, then added that he nevertheless expected the economy will "generally be better" in the days ahead.

First Lady Nancy Reagan, in a black and white satin dinner gown by Bill Blass, was at the president's side to see President and Mrs. Suharto off at the end of the evening. Tien Suharto clutched her White House program and other dinner mementos. President Suharto waved good-bye, his diamond ring flashing in the night. Guest list for last night's dinner:

Widjojo Nitisastro, coordinating minister for economic, finance and industry affairs, and Mrs. Widjojo

Mochtar Kusumaatmadja, minister of foreign affairs, and Mrs. Mochtar

Sudharmono, minister/state secretary, and Mrs. Sudharmono

Adnil Hasnan Habib, ambassador to the United States, and Mrs. Hasnan Habib

Air Vice Marshal Kardono, military secretary to the president

Achmad Djumiril, director general for protocol and consular affairs

Moerdiono, secretary of the Cabinet

Munawir Syadzali, director general for political affairs

Joey Adams, comedian, and Cindy Adams, author

Toeti Adhitama, Eksekutif magazine

Carl B. Anderson Sr., chairman, An-Son Corp.

James A. Baker III, chief of staff and assistant to the president, and Susan Baker

James L. Barrett and Merete Barrett

Stephen D. Bechtel Jr., chairman, Bechtel Group Inc., and Nonie Ramsay

Eleanor Lambert Berkson, public relations executive

Daniel J. Boorstin, Librarian of Congress, and Ruth Boorstin

William E. Brock III, U.S. trade representative, and Laura Brock

Vice President George Bush and Barbara Bush

Craig Claiborne, author, food writer, The New York Times

William P. Clark, assistant to the president for national security affairs, and Joan Clark

Kent Crane, Crane Group Ltd.

Charlotte Curtis, associate editor, The New York Times

Michael K. Deaver, deputy chief of staff and assistant to the president, and Carolyn Deaver

Rep. Edward J. Derwinski (R-Ill.) and Patricia Derwinski

Michael D. Dingman, chairman, Wheelabrator-Fry Inc., and Jean Dingman

Paul W. Douglas, president and CEO, Freeport-McMoran Inc., and Colette Douglas

Guilford Dudley Jr., former ambassador, and Jane Dudley

Mrs. J. Clifford Folger

Gen. Charles A. Gabriel,, U.S. Air Force chief of staff, and Dorothy Gabriel

Christina Ginsburg

Roy G. Gonzalez, Gonzalez International Services, and Marie Gonzalez

William Harvey, president, Hampton Institute, and Norma Harvey

Robert Hefner, GHK Companies

William A. Hewitt, chairman, John Deere Inc., and Patricia Hewitt

John H. Holdridge, assistant secretary of state for East Asian and Pacific Affairs, and Martha Holdridge

Roy Huffington and Phyllis Huffington

John Hughes, assistant secretary of state for public affairs, and Vera Elizabeth Hughes

Daniel Mahoney and Kathleen Mahoney

Stephen J. Malkmus and Mary Malkmus

Edwin Meese III, counselor to the president, and Ursula Meese

Edwin Meese Jr. and Leone Meese

Mabel Mercer, jazz singer

John C. Monjo, American charge to Indonesia, and Mrs. Monjo

Wendy Morgan

James Munn and Mrs. Munn

Alwin Niklolais, choreographer

Arnold Palmer, golf pro, and Winifred Palmer

Milton Petrie and Carroll Petrie

Freda Poundstone

Donald Regan, secretary of the treasury, and Ann Regan

Paige Rense, editor, Architectural Digest

Selwa Roosevelt, chief of protocol, and Archibald B. Roosevelt Jr.

Gary Schuster, White House correspondent, Detroit News, and Mrs. Schuster

George Shultz, secretary of state, and Helena Shultz

Alexis Smith, actress

Bernard E. Smith Jr. and Jean Smith

Rep. Charles W. Stenholm (D-Tex.) and Cindy Stenholm

W. Clement Stone, chairman, Combined Insurance Co., and Donna Stone Pesch

Alfred Taubman and Mrs. Taubman

Edward R. Telling, president and CEO, Sears, Roebuck and Co., and Mrs. Telling

Paul Thayer, chairman, LTV Corp., and Mrs. Thayer

Leroy Tombs, chairman, National Association of Black Manufacturers, and Mildred L. Freeman

Gloria Vanderbilt

Frederica von Stade, mezzo-soprano, and Peter Elkus

James Wieghart, executive editor, New York Daily News, and Sharon Wieghart

Byron White, Supreme Court justice, and Marion White

George Will, columnist, and Madeleine Will

John A. Zenko, president, Telemedia Inc., and Jere Zenko