After cutting out your hem facing, make sure your notches are marked, and front and back hem facing is differentiated from each other (three notches at center back differentiate back from front). If you lose track, the front hem facing is wider than back hem facing.
On straight edge of hem facing, fold 1/4'' in towards wrong side of fabric.
Top of hem facing folded 1/4'':
Opening up folds, pin side seams of hem facing together (right sides together).
Stitch together at 5/8'' seam allowance.
Trim down side seams and press towards front of bodice. Press down straight edge of hem facing.
Pin hem facing to bodice. Pin right side of hem facing to wrong side of bodice along curved hem matching all notches, and side seams.
Make sure bodice side seams are facing in opposite directions to eliminate bulk.
Stitch 1/4'' seam allowance along bottom of bodice/hem facing.
Press hem facing down. Optional step: understitch seam allowance to bodice, make sure seam allowance is pressed up towards bodice).
Press hem facing up towards bodice, match side seams and pin evenly distributing across bodice. Top stitch hem facing to bodice 1/8'' (or 1/16'') from edge of hem facing.
TIP: If your fabric has a lot of stretch to it (an open weave linen or gauze) it is possible the hem facing will be prone to stretching. If you are finding your hem facing isn't lying flush as you pin it is okay to remove a little width from the top of the hem facing side seam by doing a slightly larger seam allowance). The pattern factors in a slight amount of stretching and already removed a bit of width from the hem facing width (at the fold). As stretch factor varies between textiles this is a good thing to keep on your radar.