A Rockville computer firm and its president have been found guilty of defrauding the General Service Administration by altering resumes of consultants provided to federal agencies.

Both Icarus Corp. and its president, Herbert G. Blecker, were found guilty by a federal jury in Alexandria of making false claims to the government. Blecker faces up to 30 years in jail and up to $60,000 in fines; Icarus could be fined up to $80,000.

Under indictments brought by a special Justice Department task force on corruption at GSA, Blecker, Icarus, and Peter C. Loux, a former employe of Computer Sciences Corp., were charged with participating in a scheme to defraud GSA through a computer contract awarded by the agency in 1972 to Computer Sciences.

Loux had been charged with steering subcontracts under the main contract to Icarus in return for kickbacks funneled to him by Blecker through various bank acccounts.

The jury Saturday acquitted Loux of all charges against him and acquitted Blecker and Icarus of those charges dealing with conspiracy and kickbacks.

Barnet Skolnik, Loux's attorney, told the jury the money his client received from Blecker was for previous consulting services.

But the jury agreed that Blecker and Icarus had altered the resumes of their consultants so they would be paid by GSA at higher hourly rates than they were entitled. Under the GSA payment schedule, the consultants' hourly rates rose with their years of relevant experience and education.

One Icarus employe testified, for example, that she was described on a resume as a teacher of technical subjects for the Air Force. In fact, she said, she had been a fourth grade teacher and managed a thrift shop on an Air Force base in Japan.

If the number of years of computer experience listed by Icarus on her resume had been accurate, she said, she would have to have been nine years old when she entered the field.

Icarus' work was for GSA's Infonet computer system, which allows federal offices all over the country to make use of centralized computers through terminals around the country.