Barbara Deckert answered:
Again, I did it the lazy way. The fabric is a knit so it won't ravel, and folding the raw edges under would be bulky, so I just folded the edges under and topstitched with some silk buttonhole twist that I had laying around (probably at least 20 years old!) using a #18 needle; then I trimmed the fabric close to the stitching. On the collar, where the wrong side shows, I topstitched again with the silk twist from the wrong side, very close to the bobbin thread of the first topstitching so the silk twist is on both sides of the collar, down just past where it folds at mid-torso. I didn't even try to use silk twist in both the needle and bobbin of my machine.