Cast on 125 stitches to make it a tad longer. Added a 6 st seed stitch border on the right side only to resolve the curling issue. After knitting the rectangle, do not bind-off…stitch up the seam, remove the provisional cast on, add these stitches to the live stitches on the needle and knit a seed stitch border across both the back and front sections matching the stitches to the 6 st border.