I cut rabbets either on the shaper, or using a groover on the table saw. Below is a 1/2 inch groover, sitting on some rough lumber. The dark, perpendicular marks on the board are from the stickering process. As lumber is sawn, ripped to thickness, it is stacked with spacers between boards, called stickers, to allow air to move freely and the board to start the drying process.
The middle image, the drawing, is an example of the design process of a molding profile.