I have been wanting to do this for awhile. Its just nice too see actual pictues instead of drawings . I have had customers cut the armpitts out too many times not knowing how to skin there deer and elk or any antlered or horned animal out properly.
Step 1: If you can, hang the deer but the hind legs, it is much easier to skin

But if its in the field you can do this with the animal layin gon the ground too. First thing I do is cut around the front knee joint , then take your knife and cut up th eback of the leg where the whit hair and brown hair come together. Noe on other species you'll have a hair pattern where the long hair meats shorter hair. Just go straight up to the armpit.