@IguanaGreg MashaKnots has a video on straight edges in which she explains how to apply straight edges to any normal pattern, but if you want you can also check out the straight edges tutorial I have written. For this pattern you'll need to add an extra string on either side. Then in the even rows of this pattern where there is string sticking out a bit at the sides you add a bf knot on the left and a fb knot on the right.
KrazyKnotz
