President Carter's top economic salesman encountered a "show me" skepticism Wednesday while peddling the government's anti-inflation program to midwestern businessmen.

Despite widespread endorsement of the president's goals of a ceiling on wage and price increases, many of the 1,000 persons attending the White House's first anti-inflation forum also voiced doubts that the cost of living can be curbed voluntarily. Yet many vowed to try.

"I cannot speak for all the business leaders of St. Louis or the country, but I can say for my own company that you will receive complete cooperation," promised R. Hal Dean, chairman of the board of Ralston Purina Co.

"I'm somewhat optimistic but not completely," one businesswoman said. "I see nothing in this whole program that attacks the main source of the problem, and that's the federal government. I don't know if I can afford Washington any more."

Others made outright predictions of failure. "Whenever we've had controls, voluntary or mandatory, there's been a temporary reduction in prices but then prices have taken off," said Lawrence K. Roos, president of the Federal Reserve Bank of St. Louis.

Carter made a brief appearance at the forum via a telephone call piped throughout the convention center. After plugging his plans to hold wage increases to 7 percent and price rises to 5.75 percent in 1979, the president fielded three pre-arranged questions from the audience.

"What we need now is a public profession of support from the hundreds of business and labor leaders in this country who can make it or break it," he concluded.

Spearheading the St. Louis program - billed by presidential aides as "another Camp David" - were Robert Strauss, special representative for trade negotiations; Secretary of Labor Ray Marshall; Alfred Kahn, the newly named chief inflation fighter, and Charles Schultze, chairman of the council of economic advisers. The forum will be repeated in Hartford, Conn, next week.

"This is a tough, this is a positive and this is a "do-able' program, said Strauss, in keeping with the forum's purpose as a pep talk and an opportunity to assess grassroots support for the plan. Strauss later acknowledged that the nation faces a recession if the program fails.

Judging by the applause and seconding speeches from the audience, parts of the program had enthusiastic support - particularly when it comes to trimming the federal deficit, eliminating unnecessary regulations and cutting government employment.

Regulations, meanwhile, were getting enthusiastic attention from Douglas Costle. Environmental Protection Agency administrator and newly designated head of the president's Regulatory Council, who conducted a news conference in Washington yesterday.

Costle said his first priority is to "develop a unified calender of major regulations," which he said would" help identify areas of opotential duplication, overlap or inconsistency in the regulations emanating from the 179 regulatory units of the federal government.

Costle warned against viewing regulations as inflationary just because they cost money. "Regulations are not inflationary if the benefits exceed the costs."

And Pat Rich, president of the League of Women Voters here, said voluntary efforts' whether in fighting inflation or saving energy, historically have been "a lot of talk and very little done."

The Carter plan, denounced Tuesday by AFL-CIO president George Meany, also received only lukewarm support from the St. Louis AFL-CIO Labor Council.

"If industry will do its share to hold down prices at or below the guideline level, we in the area labor movement have already demonstrated we will hold up our end of the bargin on the wage side," Robert J. Kelley, labor council president, said.

"I applaud his effort," Kelley added, noing his reservations about the program's ultimate efficiency. "My God, it's got to be tried."

Though optimism hardly bubbled from the participants as they filed out after three hours of jawboning, many seemed to echo the sentiments of one trade associate executive:

"I think there's no choice but to give it a shot even if the odds aren't very good. And I think there's a need for a wait-and-see attitude. Anybody who comes with a great big negative or a great big positive is blowing smoke.

"It gets down to the basic question. Are enough people going to pull the [WORD ILLEGIBLE] - together.?"