Rep. John J. McFall (D-Calif.), the former House majority whip, was found guilty yesterday on one of three counts of misconduct by the House committee investigating South Korean influence-buying.

The committee recommended that the full House impose the lightest possible penalty: a reprimand.

Rep. John J. Flynt Jr. (D-Ga.), chairman of the Committee on Standards of Official Conduct, announced the findings after a 2 1/2-hour deliberation, which was interrupted several times for votes.

Specifically, the committee voted, 8 to 3, to find McFall guilty of failing to report as a campaign contribution $3,000 in cash he received from South Korean businessman Tongsun park in 1974.

McFall put the money in a secret office account in increments, and later borrowed part of it to help his daughter buy a car.

The committee, however, defeated, 9 to 2, a charge that McFall converted the money to his own use. Members also voted, 7 to 4, against the final charge: that McFall broke House rules because the money he took and the favors he did for Park could have been construed as influencing his duties as a member of Congress.

The committee then voted, 8 to 2, to recommend to the full House that McFall be reprimanded. When a member is reprimanded, the findings of guilt against him are read before the full House, but he doesn't have to be present. The penalty does not affect voting rights.

"I feel my reputation for integrity and honesty have been upheld by the committee action and I've been completely vindicated," McFall said.

He said the reprimand related only to "a technical matter" - the failure to report the campaign contribution - and predicted that his constituents would take that into account in next month's election.

The committee was scheduled last night to hear final arguments in the case against Rep. Edward J. Patten (D-N.J.). He is accused to passing off as his own money two $500 campaign contributions to the New Jersey Democratic Committee when he knew the money had come from Tongsun Park.

Committee member Millicent H. Fenwick (R.N.J.), clearly upset by the committee action, stormed out of the room before the formal announcement. Later she told reporters she thought all three counts of the charge had been proved and that the penalty wasn't harsh enough.

Fenwick added that she felt the committee vote was sincere. "If's the point of view that distresses me," she said. "These offenses against ethics are really far more serious than the [other committee members] seem to feel they are."

The committee voted last week to recommend disciplinary action against two other members, Reps. Edward R. Roybal and Charles H. Wilson, both California Democrats. It was recommended that Wilson be reprimanded and the Roybal be censured - a more serious penality - for making false statements about money they received from Park.

Yesterday's actions all but finished the 18-month-old House investigation which grew out of reports of payments to members by Park. The committee also tried to question former Korean ambassador Kim Dong Jo about accusations that he too had made payments to members to encourage their support for aid to South Korea. Those efforts were stymied several times, leading to the departure of special counsel Leon Jaworski and the effective end of the investigation.

The committee was briefed Tuesday by William H. Gleysteen Sr., the U.S. ambassador to South Korea. But members have refused to comment on the meeting and on how - or if - they will respond to Kim's recently received letter describing some of his activities.

Flynt had announced with some fanfare earlier that Kim, the ambassador in Washington in the early 1970s, had agreed to cooperate with the committee in telling of his relations with members of Congress. Kim is suspected of making or directing payments to several current House members. But it has been reported that he acknowledged making only one contribution to a former member. That incident had already been publicized.

During final arguments in the McFall case yesterday, John W. Nields Jr., committee chief counsel, attacked the way McFall had handled the money he received from Park.

Nields noted that McFall's top aide, Raymond Barnes, had destroyed a note from Park identifying the cash as a campaign contribution and that Barnes had deposited the money in a bank on several different occasions because he thought it would look bad to deposit such a large amount all at once.

Nields said letters McFall wrote to the president of South Korea at Park's request "leave the impression than Park had been able to purchase some influence from Congressman McFall."