A system for manufacturing from heated plastic sheet material a molded siding product having a rough-textured surface includes a rotatable backing roll having an elastically deformable rim and an embossing element having a moveable embossing surface in compressive engagement with the backing roll. The circumferential surfaces of the backing roll and embossing surface define a contact patch and a nip point. A rough-textured pattern is impressed onto the heated plastic sheet material moved through the nip point. A supply of cooling liquid at least partially sets the heated plastic sheet material to retain an impression of the rough-textured pattern. Respective first and second guide rollers are located higher than the nip point and create a valley defined by the heated plastic sheet material, such that the cooling liquid is collected in a puddle on the heated plastic material proximate the nip point.