From the Warbonnet description:
The [tarps] have lightweight low-stretch polyester edge binding on the ridge seam. The binding along the ridge seam makes for an extra-strong low-stretch ridgeline seam that eliminates the need for a separate ridge cord, it also means you'll never need to seam seal the ridge seam.
Have you followed this model or example, and if so, what do you use?
Per the previous post, there are products specially made for this, but I notice that 1/2" (13mm) satin polyester ribbon weighs 2oz per 100ft and has an estimated breaking strength of 100lb. Is this what Warbonnet encorporates?