Are you using a sewing machine? If so, I would pick up what is called a "double needle" which sews two lines of top-stitching (the stitching you see on the outside/right side of a garment) at equal width apart, which makes the hem less likely to roll and also looks professionally finished. This tool is great for knits since it creates a stretchy type of stitch which is good for knits.
Sometimes having a wider hem will help with flipping and rolling, and the very last attempt would probably be sewing the raw edge of the knit between some hem tape or bias tape and then heming the tape to to the body of the skirt to add some weight to the hem and make a crisper hem that shouldn't flip. It also won't stretch, so that is something to think about. Sometimes you can sew the raw edge to a piece of wider lace, then sew the lace up to the body of the garment as well.
Having too tight of stitch tension on a knit fabric can create a taut hem that almost indents into knit fabric and that can be part of the reason for the flipping.
Pinning and pressing the hem prior to sewing might help as well.
