Rep. Robert L. F. Sikes (D-Fla.) told freshman Democrats yesterday tht they would be placing him in "double jeopardy" if they uosted him as chairman of a House Appropriations subcommittee after he had already been reprimanded by the House for conflict of interst and violations of the code of ethics.

Sikes, in a 12-page presentation, contended that it was not his stewardship of the military construction Subcommittee that was under attack. "There was no finding of misuse of my power of chairmanship," he said.

He also said his attackers were "strangely indifferent" to other House members accused of misconduct, and implied that they were after him because of his strong support of defense spending.

Sikes said he did not feel the findings of the House ethics committee that he had violated ethical standards were justified, and asked the freshmen to judge him on the basis of his overall performance as chairman.

But the freshman and some sophomore Democrats who were present repeatedly pressed Sikes to explain why his ethical conduct shouldn't be taken into consideration in weighing his right to be re-elected subcommittee chairman.

Many of the freshmen said they wanted to read the ethics committee report before making up their minds on how to vote on Sikes. However, one freshman, who asked not to be identified, said, "It wasn't much of a defense. After all, our image and the image of the House is at Sake."

The practice of chairmen and subcommittee chairmen appearing before incoming freshmen to justify their stewardship of their committees was started two years age, following those meetings, the 75 new Democrats threw their support behind outsting three senior and powerful committee chairmen, the first time since Democrats began electing chairmen that any had been thrown out.

This time, only Sikes seems to be in serious difficulty, though freshman class president Rep. Jim Mattox (D-Tex.) said some of the 47 members of the freshman class had "some questions" about Rep. James J. Delaney (D-N.Y.), nominated for Rules Committee chairman, and Rep. Robert N. C. Nix (D-Pa.), expected to seek the chairmanship of the Post Office and Civil Service Committee.

Last summer, upon the recommendation of the ethics committee, the House voted to reprimand Sikes for violations of the ethical code of conduct.

He was reprimanded for failing to report ownership of about $8,000 worth of stock in Fairchild Industries as House rules required; using his official position to establish First Navy Bank on the Pensacola navy base in his district, and then asking to buy and getting 2,500 shares of the bank's stock; and getting legislation passed to allow commercial development of a tract of land in Florida in which he had a financial interest.

Sikes was chairman of the Military Construction Subcommittee at the time he was using his influence to get the First Navy Bank established on the Navy air base, and Rep. Toby Moffett (D-Conn.) asked Sikes yesterday whether that did not constitute using his chairmanship to benefit himself.

"I made the same recommendations in helping the bank that I made for many other businesses in my district," Sikes answered.

In addition to Sikes, ethics committee Chairman John J. Flynt Jr. (D-Ga.) came in for some hard questioning by the freshmen.

Flynt was asked whether the upcoming investigation of Korean influence-buying shouldn't be moved out of his committee since, as Mattox said, "Four members of your committee may have come under Korean influence" or taken trips to Korea.

Flynt said he was reliably informed there was no Korean involvement by any sitting member of his committee, but refused to say that that extended to taking trips to Korea. "Twenty to 50 per cent of the House has probably taken those trips," he said.

But Flynt added that he had asked that a rule be passed to allow members of his committee to disqualify themselves and be replaced if there were a problem.

The Democratic Caucus is expected to vote on committee chairmen next week and Appropriations subcommittee chairmen the week after that.