I'm not the sock maker in these here parts, but I agree that if you don't mind a seam, then do it flat to start with. You might want to add a stitch at each end of the ribbing to give you a seam allowance.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog