Hand rolled hems are so lovely, and with a little practice and a few tricks, quite easy to do (if a bit time consuming).
Begin by machine stitching 1/4″ from the edge along the entire edge.
Press the stitching flat.
Thread a hand sewing needle with matching thread. For a delicate fabric such as this silk charmeuse, use a small needle with a narrow eye to minimize the visibility of holes in your fabric.
Now find something you can use as a weight. This is so you can pull the fabric taut as you sew. I’ve read one recommendation to use a fabric-covered brick, but this craft supply caddy worked just as well. Books would also be fine.
Trim close to the stitching as you go, trimming about six inches at a time. Trimming only a bit at a time will minimize raveling.
Try to get very close to the stitches.
Anchor your thread at the edge of the fabric by creating a few backstitches there.
Pulling the fabric taut, hold the fabric edge between your thumb and forefinger, and roll toward you. Roll it until the machine stitching is hidden within the roll.
Use a slipstitch to stitch the hem. To do this, bring the needle out through the folded hem. Now create a tiny stitch between the folded edge and the garment fabric, catching only a few threads of the garment. Slip the needle through the fold for 1/4″ and back out, as shown in the above photo. Alternate the tiny stitch with the 1/4″.
Continue until edges are completely hemmed.
Do not press this seam flat when you’re done. You want it to have a nice soft roll to it.