Barb is right, as she always is. I've seen many hemmed kilts. I even purchased one from Scotland that came hemmed. As Pleater says it adds to the swish if the fabric is light. There is always someone who is going to tell you you can't do it. I normally ask why? And if they can't give me a cogent answer I disregard the proclamation of these folks. Hemming your kilt is much simpler than getting a kiltmaker to redo it.