Dear White Pages,
If you haven't done a rolled hem before, you need practice if you purchase a foot for your machine. Here's an alternative method that gives a fine finish.
Fold over the hem allowance, and stitch close to the FOLDED edge, not the raw edge. Cut away the raw edge right up next to your stitching. Now, set your machine to do a very short stitch (1-1/2 or 2) and a wide zigzag (my machine goes up to five). With the left swing of the needle posed to the left of the remaining hem, zigzag around. I'm assuming that when you say "flimsy" you mean that the fabric is sheer. The hem will roll by itself.
Teri