The Art of Crochet by Teresa explains how to sew together crochet ribbing. Thread a tapestry needle and align the edges of the crocheting project. Sew the first stitch together and secure with a knot. Sewing through the top of the stitch on the edge will help prevent distortion and create a neater look for the ribbing. Pick up the back loop and align it with the stitch on the opposite side. Continue all the way across, sewing through the same stitch. It will push the top of the stitches up, continuing to form the ribbing so there will not be a visible seam. The needle will be inserted below the two loops at the top of the stitch. Continue across until the seam is sewn shut. Sew through the two stitches at the edge. Make a knot and sew in the tail, weaving it right between the stitches. Cut off the remainder of the tail to complete the project.