Drop leg knifes are those knives that are strapped to the side of the leg, most frequently for tactical or combat purposes. A drop leg sheath allows the knife to be strapped to the leg and waist, keeping it within reach should circumstances dictate its use. Getting it to stay secure on the leg requires an added strap that goes around the thigh. You can quickly fashion such a strap with nylon webbing and a slider buckle, all found at most climbing stores or outdoor outfitters. No sewing is required.
Attach the sheath to your waist belt and place the knife into the sheath. Strap it to your leg.
Thread the 1.5 inch nylon webbing through the two bottom loops off the sheath and wrap it around your lower thigh. Mark where the strap ends connect.
Add a slider buckle to one end of the strap and thread the opposite end through the sliders. Pull the strap so it is snug, but not tight. Do not over-tighten and cut off circulation.
Cut off any excess strap. As a rule, keep no more than three extra inches on the strap. This extra allows adjusting in the field should you be wearing more than one layer (such as pants along with long underwear). Melt the cut end of the nylon webbing with a lighter flame to prevent frays.