Applique shirt assist please!

[trekkie2]

I know that this is not really a sewing site, however I know that many of you have made mickey head appliques and I have a sewing question ( Since I dont do that much) I have a really great piece of knit that I want to make into a head. I plan to wonderunder it to the shirt and then was wondering if I simply sew around it leaving a small edge will the knit "roll up" forming an interesting edge or just look homemade? Would it be better to actually satin stitch around the edge? thanks for the ideas and help.