|I'm working in a blouse weight silk satin which shows all pin marks, and even sometimes needle marks if tacking. To get the patch pocket held in place before stitching I found a light adhesive webbing strip, as used for hems, to be very handy. I lay the bodice piece on the ironing board and stabbed through with four pins to mark the corners, just inside the finished placement line, cut narrow strips of the webbing and
placed them between the pins. The pocket with the seam allowance already pressed under goes on top of this, pressing as you go. It was a bit fiddly to get the pocket on without the webbing moving, so I guess I could have tacked the webbing in place and pulled the stitches out from the wrong side, but I just used the iron to touch the pocket down on the bottom strip, then worked on each side, repositioning the webbing as necessary. After that it was easy to do the top stitching.