Best way to cut relief on back of casing
I'm trimming the windows and doors inside my house. I'm making my own casing from 1x4 poplar. I'd like to cut the relief on the reverse side of the casing to ensure the tightest possible fit to the jamb and wall. I'm wondering how other people cut that relief.
I'd like to cut the relief 2 1/2 wide and about 1/8 deep. That would give me 1/2" feet on both edges of the casing.
Ideally I'd like to do this with a router so I don't have to disturb the setup I've got on my other tools. So, in short, has anyone done this with a router? Can you describe the bit used and the setup?