A federal grand jury here returned indictments today charging the president of a Silver Spring firm and a salesman for a Bladensburg firm with billing the General Services Administration for office supplies they never delivered.

The grand jury charged Clifton Johnson Jr., a salesman for Atlantic Office Supply Co. of Bladensburg, with conspiracy to defraud the federal government. George H. Smith, president of Raybil, an office supply firm in Silver Spring, was charged with four counts of filing false claims.

Johnson, a 42-year-old Washington resident, and Smith, a 63-year-old Silver Spring resident, are subject to maximum penalties of five years in jail and a $10,000 fine if convicted of the charges.

The grand jury here has indicted 47 businessmen, GSA employes and employes of other government agencies so far in its investigation of bribery and corruption in the government's massive housekeeping agency. Forty-two of them have been convicted and 33 who have been sentenced so far have received jail terms ranging from 15 days to four years.

The U.S. attorneys office here said more indictments are expected.

Smith was charged with submitting claims to two Washington GSA stores requesting payment for 830 dozen Flair pen refills between June and October 1977. Not a single refill was delivered even though the GSA paid Smith for the four orders, according to the indictment.Johnson was charged with delivering two televisions, six clock radios, three radios and four cameras to various GSA store managers who paid the false claim his firm submitted for office supplies which were not delivered.

The indictments do not say how much money was involved in the false billings.

In earlier indictments, two officers of Johnson's firm were also charged with conspiracy to defraud the federal government. Thomas R. Willingham, the president of Atlantic Office Supply Co., and Alberto A. Esteva, the vice president, have both pleaded guilty to the charges and are awaiting sentencing.