Good morning, I am knitting a scarf with a free pattern from Misti International and it uses the Eve's rib. It had a ruffle on each end, but because its for a man, I did not do that. So, I cast on with 15 stitches as indicated and knit a few inches. Well, I think its too skinny and would like it a little wider but I can't figure out what cast on combination so that it will work.

Any one have an idea?
Thank you!