The first -- and thus far only -- discount commission certificate or scrip to come out of a price-fixing case settlement involving six Montgomery County realtors will go on sale tomorrow.

Several thousand other class-action plaintiffs are due to receive their certificates in the future.

The owner of the scrip who placed the classified advertisement is Hugh Latimer of Potomac. Latimer sold his Rockville home in October 1976 through Colquitt-Carruthers Inc. and paid a selling fee of 7 percent. Colquitt and five other real estate companies were convicted in September 1977 of conspiring to raise commissions from 6 to 7 percent. The realtors have appealed the conviction.

Customers who sold houses through these realtors between September 1974 and April 1977 entered into a class action in an effort to get compensation. To avoid a trial that could have resulted in triple damages and bankruptcy for some of the companies, the defendants agreed to a settlement.

This would entitle each customer to sell his or her home at a 5 percent commission, or 1 percent off the going rate. The scrip could also be sold to another person selling a house.

Latimer, a Washington attorney, is the only one out of approximately 3,000 customers affected by the class action who has has settled independently. He said he had hoped for a cash settlement, but in the end accepted essentially the same scrip as that proposed in the class action. All he gained, Latimer said, was time, a chance to offer his scrip for sale ahead of all others.

Latimer's certificate may be used to sell a house anywhere in the Washington area; It could also be sold a second time before being used with a realtor. It can be honored only by the six realtors in the case: Jack Foley Realty, Bogley, Colquitt-Carruthers, Robert L. Gruen, Shannon & Luchs and Schick & Pepe Realty.