President Carter, vowing to "go a second mile to accommodate" President-elect Ronald Reagan, flew to Camp David yesterday for a few days of rest after saying that he hoped the last months of the Carter administration will also be the best.

Before leaving the White House by helicopter with his wife, Rosalynn, the president named Jack H. Watson Jr., his chief of staff who headed the Carter transition team four years ago, to work with the Reagan transition organizaiton.

Carter, in a pensive and reflective mood, also spoke at length yesterday morning with reporters, analyzing his defeat, which he said he did not consider a rejection of him personally, and looking back on the four years of his presidency.

He said he did not intend to take an extended vacation, and expressed uncertainty over his plans after leaving office beyond returning to Georgia to write his memoirs. In the meantime, he stressed, "The full constitutional responsibility and authority [of the presidency] will be mine."

The president reflected his determination to cooperate with his successor in discussing the pending strategic arms limitation treaty (SALT II), with the Soviet Union, the issue that most sharply divided him and Reagan.

"If Gov. Reagan's professed desire to withdraw the SALT II treaty from consideration, to start with a fresh approach, proves to be acceptable to the Soviets, then Gov. Reagan can expect my full support of whatever effort he makes," Carter said.

He also defended his handling of the Iranian hostage crisis, which political advisers believe was the single most decisive factor in his overwhelming defeat.

"I doubt if any successor mine, including Gov. Reagan, would materially change the posture that we are maintaining, and I doubt that anybody in my position the last 12 months would have done substantially different from what I did," he said. "I don't know of anything that could have been done better or differently."

Sitting behind his desk in the Oval Office, Carter said he had spent the first two years of his presidency as "a student," and that Reagan, "will have the same things to learn that I had to learn." He said he believed he had been a "strong president," and, citiing particularly the Panama Canal treaties, added that he hoped "that history will show that I have never flinched in dealing with the issues that some of my predecessors have postponed."

The president, making frequent use of the word "inevitable," had a fatalistic tone as he discussed the election results and the presidency, suggesting that the forces that had buffeted him would do the same to Reagan. He said he agreed that the hostage issue and the preelection moves in Iran suggesting a release of the 52 Americans were "a factor in his defeat and served to fuel the frustration that was so evident in Tuesday's election results.

"But, I can't say it was more important than the high interest rates or other factors that would influence the American people," he said.

In a long, rambling answer to a question about the state of the presidency, Carter cited some of the factors he thought contributed to his defeat. He said the Cuban refugee situation "hurt us badly," not just in Florida but nationwide, because "it made us look impotent."

There was also "some downside" from the Middle East peace process among Jewish voters, he said, adding that he had passed up opportunities "to demagogue this issue, referring to Israel's territorial future and the status of Jerusalem."

But in the end, the president said, the key factor "was just a frustration that there are some unresolved challenges and problems, and the natural tendency is to vote against incumbents in the U.S. Senate, the Congress and the presidency."

Carter added:

"The fact is that it's very difficult for someone to serve in this office and meet the difficult issues in a proper and courageous way and still maintain a combination of interest-group approval that will provide a clear majority in an election time . . .. I hope that one of the things that come out of the election is a realization of the difficult decisions made here, the need for maybe a closer cooperation and coordination between the president and the congressional leadership . . .."

Asked if he believes Reagan will achieve the goals he has set for his administration, Carter replied with a tone of skepticism.

"I'm sure Gov. Reagan will do the best he can to carry out his campaign commitments -- which are deeply felt by him, I'm sure -- to restore as much as possible our nation's preeminence in some areas where we have not been able to exert our will to dominate others," he said. "But the inexorable historical movements are that we don't have control over some things that we formerly did . . .. Whether anybody could do more in the future, I can't say."

The president, carrying a briefcase, and Rosalynn Carter left the White House shortly after noon for their helicopter trip to Camp David. A large number of White House aides and senior administration officials witnessed their departure and applauded as the Carters passed by. Some young women held a hand-made sign that read: "We love you, Mr. President."