Larry, DO NOT use your tablesaw to cut a door for height. Hopefully you meant hand held circular saw.Take a piece of 1/4" plywood and nail or screw a straight edge to it. The plywood has to be as long as the widest door and wide enough to clamp to door { 10" is usually enough}. Run saw base against straight edge and thru plywood. This will give you blade setting and protect door from scratching by saw base.Clamp this jig to door. Because you are unfamiliar with trimming doors I will show you the safe way to get a perfectly clean cut. Put a sharp combination blade in BACKWARDS in your saw ( 40 teeth in a
7 1/4" blade will do}.Set for 1/4" depth of cut, then make this scoring cut.When done, turn blade around the correct way. Set base so blade will be a full tooth below door, then cut. You do not have to tape the cut or knife it either. Now for those people that are more familiar using a skilsaw, don,t bother putting blade in backwards. Instead start at end of cut and PULL saw backwards with a 1'4" depth of cut. Then set saw base as usual and push saw thru to complete cut. This method can be used to cut veneered panels, laminated doors or anything that is prone to chipping. You simply make a shallow score cut then finish cutting with full depth. Mike