A quarter-inch seam is where ever you have to place the fabric to get a true quarter-inch seam.
That's not very helpful, I know.
You're going to need to sew some scraps, then measure the finished patch to get the correct finished size before you can know where to place the edge of the fabric with regards to your foot.
Last edited by Peckish; 07-09-2018 at 04:08 PM.