The addition of silicone rubber fine particles to a composition comprising an organopolysiloxane having at least two alkenyl groups, an organohydrogenpolysiloxane having at least three SiH groups and a catalyst yields a composition which when coated onto any substrate, forms a coating whose surface is extremely reduced in gloss and highly uniform. Using the coating of the composition as a release sheet, synthetic resin sheets having matte surfaces can be readily manufactured.