Had he paraphrased yet another of John F. Kennedy's quotes, Ronald Reagan could easily have identified himself as "I'm the one who accompanied Nancy Reagan to Europe." In the end, Mrs. Reagan may not have won Europe the way Jackie Kennedy did Paris in 1961, when Kennedy described himself with that now-famous line, but Nancy Reagan was clearly the winning Reagan.

As James Rosebush, her chief of staff, explained it, Americans want to see her "with people, learning the culture and doing fascinating things like dancing the flamenco . . . You get Nancy Reagan with people and Ronald Reagan working on policy, and Americans like that. "What you see is a lot more affection because she can go into places he can't go," said Rosebush, who personally advances Mrs. Reagan's foreign itineraries. "This is what she can do for the president."

If she didn't have top billing at the start of the 10-day, five-nation Reagan roadshow, she came home with the trip's Oscar as the best all-around performer. For that the White House can be thankful. In fact, Reagan singled her out for a special salute when they returned to Andrews Air Force Base.

"I don't mind telling you, there's a very special person who does a wonderful job on these trips," Reagan said. "Whether meeting with leaders and parents concerned about drugs in Bonn, Lisbon or with the Holy Father at the Vatican, or doing a pretty fair flamenco in Madrid -- I think Nancy is one of the best ambassadors America has ever had."

In contrast to the president's trip, in which there had been some glitches, as White House chief of staff Donald Regan admitted at one point, an aide to the first lady said "there hasn't been a single one in Mrs. Reagan's program."

It had been strictly the president's show the Sunday the Reagans visited the Bitburg military cemetery and Bergen-Belsen concentration camp. She had reservations about the inclusion of Bitburg on Reagan's schedule, that day she was tight-lipped and pale as she and the president walked hand in hand past the graves.

"But she knew that once Bitburg was selected, and the president was going to stick to it, that the other side had to be taken care of," one White House aide said.

At Bergen-Belsen, she was clearly moved listening to her husband's speech. "All she could think of," Jennefer Hirshberg, Mrs. Reagan's press secretary, said later, "was of a very close friend who had been at Bergen-Belsen." The friend survived and the White House declined to identify the person.

Certainly, her activities became the antithesis of the president's, which from the outset were riddled with controversy over his visit to Bitburg.

While France's Franc,ois Mitterrand was upstaging Reagan over trade negotiations during the summit windup in Bonn, Nancy Reagan was holding hands with Pope John Paul II.

While Spain's Prime Minister Felipe Gonzalez was disagreeing with Reagan over his Central American policy and the U.S. military presence in Spain, Nancy Reagan was doing the flamenco under the patronage of Queen Sofia.

While Communist and socialist hecklers were preparing to interrupt Reagan's address to the European Parliament, Nancy Reagan was taking a boat ride on the River Ill past a crowd of several thousand waving Frenchmen.

"She was the star," said longtime Reagan aide and imagemaker Michael K. Deaver by trip's end.

European media coverage of Mrs. Reagan backed him up. She seemed to generate stories wherever she went. Her visit to the pope resulted in the release by the Vatican of the pontiff's three-page letter to her (an act thought to be rare for a private audience) in which he appealed for international cooperation in stamping out what he called "this grave social evil," the use of illegal drugs.

In Bonn, her antidrug campaign at one point became the talk of the seven-nation economic summit after British Prime Minister Margaret Thatcher unexpectedly brought it up over dinner. Here again the results were productive: a pledge by the leaders of West Germany, Italy, France, Great Britain, Japan, Canada and the United States to study ways of cracking down on worldwide trafficking in narcotics.

There was also a lighter side of Nancy Reagan carefully orchestrated by White House aides for American and European consumption. A photogenic and professional actress who rarely misses her cue, Mrs. Reagan gave a flawless performance in Madrid. Pictures of her doing the flamenco appeared on nightly television shows and in papers across the continent, and even Greek-born Queen Sofia, known not to be a particular fan of the dance, could not hide her delight.

Looking for opportunities in which the first lady can "participate" -- something he calls "feeling the yardage" -- Rosebush said he has found that her "concern for people" comes through in meetings with parents groups on drug abuse and that her interest in culture can best be shown through museum and school visits. The flamenco lesson was an example of the latter.

"You don't have to deduce too hard that she likes to do things like that, so it shouldn't have been too surprising that Mrs. Reagan gave flamenco a try," he said.

Throughout the trip Rosebush directed as well as assisted in Nancy Reagan's public appearances. In Strasbourg as the small boat glided past friendly onlookers straining for a glimpse of her, Rosebush quietly coached: "Turn to the other side now so those people can see you."

She turned accordingly.