With a traditional D-loop, you’ll want the loop on the inside of the knots. With a D-loop under a tied on nock set, you’ll want the loop on the outside of the knots. This will ensure your release has plenty of room in the loop.
Start with a piece of D-loop material about 4 ½” long or whatever length you know works for you. If need be, start with a longer piece of D-loop material and trim it as needed. Knowing the length serves a purpose. After you’ve setup your bow to fit you just how you like it, make another D-loop the same length and put it in your archery tool box or quiver. If your D-loop frays and/or needs replaced, you’ll have one of the correct length ready. Place the new D-loop on the string and you’re ready to go.
After tying the first knot onto the string below the nock set, pull it tight with a pair of pliers. This will help ensure the knot doesn’t slip and that you’ll have enough D-loop material to finish the knot.
The knots should also be on opposite sides of the string. This will help prevent any torque of the string by your release. After both knots are tied, place a pair of needle nose pliers into the D-loop and spread the pliers to tighten the knot.