The president of the Puerto Rico Olympic Committee said yesterday that the island commonwealth will field a team at the Moscow Olympics, a move that means U.S. citizens will compete in the Summer Games.

German Rieckehoff, the PROC president, said that 50 to 60 athletes, who by virtue of their Puerto Rican government that the PROC honor President Carter's call for an Olympics boycott in response to the Soviet invasion of Afghanistan.

Bowing to White House pressure, the U.S. Olympic Committee, which has no formal ties to the PROC, voted last week against sending a U.S. team to Moscow.

The Carter administration is trying to mobilize support for the boycott among U.S. allies. But Rieckehoff said yesterday that no one from the administration has contacted the PROC.

"I'm very surprised," he said, adding that administration pressure probably would not have affected the PROC's decision to send a team to Moscow.

Rieckehoff also said that prior to a meeting Carter has with athletes and sports officials last month, Rieckehoff cabled the White House asking for an invitation, but received no response.

"Nobody has really had time to look into it at this stage," a White House aide said yesterday about the PROC's decision. The aide refused to speculate on whether the administration would take legal steps in an effort to prevent Puerto Ricans from competing.

A State Department source said it was unlikely that an athlete from the United States wanting to compete in Moscow could establish residency in Puerto Rico in time to qualify for that island's Olympic team.

The International Olympic Committee awards Olympic franchises to countries, territories, mandated protectorates and other geographical entities independent of their government or political affiliations.

Thus, Puerto Rico and the U.S. Virgin Islands, which has decided to boycott, have had their own Olympic committees since 1948 and 1967, respectively.

Puerto Rico, as a commonwealth, a State Department source said yesterday, has "internal self-rule and makes its own decisions. And, certainly, in the Olympics it has its own national Olympic committee."

"It gets its own invitations [to the Games], it makes its own decisions and fields its own team. There's nothing new about that."

Rieckehoff said the PROC voted 21 to 3, with two abstentions, at its April 9 meetings to let each of the island's 24 sports federations make its own decision on participation.

Several federations indicated they did not have athletes of Olympic caliber and would not go, he said.But six -- track, basketball, boxing, judo, shooting and rowing -- have said they want to go and will be certified as entrants by the PROC, he said.

Gov. Carlos Romero-Barcelo and the island's legislature, backers of the boycott movement, subsequently notified the PROC that it would not get any of the $164,000 it had requested to prepare and send a team, Rieckehoff said.

He said the PROC is trying to raise $100,000 through sports events. "We will raise the money; there is no doubt about that," he said.

Angered by accusations of being unpatriotic, Rieckehoff said, "I am as patriotic as anyone else and I resent and criticize the invasion of Afghanistan. But not going to the Olympics is not going to prove anything.

"We don't think sports or the Olympic movement should be taken as an instrument of political affairs. We will participate in the Olympics under our own flag as Puerto Ricans. You have to choose your sports citizenship, and in the Olympics our sports citizenship is Puerto Rico."

He adamantly denied that the issue of statehood appeared to be picking up more support as Canadian Prime Minister Pierre Elliott Trudeau endorsed the boycott.

A boycott is unlikely to get Soviet troops out of Afghanistan, Trudeau said, but the Soviet Union must "be made to remember by whatever action we take that it loses of lot of friends, and not only among the capitalist countries."

Trudeau's statement, his strongest on the boycott, added to reports that the Canadian government likely will announce its support of a boycott on Tuesday, the eve of a visit by Secretary of State Cyrus R. Vance.

Dick Pound, president of the Canadian Olympic Association, said it is "all but inevitable" that Canada will join the boycott.

Elsewhere, the executive board of the Norwegian Sports Federation, the ruling body for all sports in that country, voted 8 to 3 to recommend to its national convention on Sunday that Norway boycott. The Norwegian Olympic Committee has voted to participate, but the federation has the power to overrule it.

In Italy, Premier Francesco Cossige hinted that his country would join the boycott.