Recently on Crafty Mamas a member was having trouble getting a consistent rolled hem on the outside curve on a ruffle corner so I made a little video to show how I would do it. Maybe you would do it differently or better but this is what works for me.
Cut the curve first, it is harder to use a square cut corner and try to round it while overlocking as the excess fabric creates drag and will slow the turning of the curve.
Keep your fingers flat across the piece so you are creating a circular pull as you sew. It might create a pucker across the bias of the fabric but shouldn't be that noticeable on a ruffle. If it is a problem use some sort of iron on removeable or washable stabiliser and that should stop that happening. I did cut off a bit of the curve but again, using a camera with one hand while doing this was a bit tricky.
The finished result:
Rolled hem on an outside curve. Forgive the little glitch seeing as I was going one-handed holding the camera at the same time.
For a tighter curve then I need to go slow, stop and lift the foot with the needle down a few times to ease around the corner.
I hope this is helpful and works for others. Let me know how you go.