First, preheat the oven to 400℉.
Pat the chicken thighs dry. In a bag, add the chicken thighs the oil and the packet of ranch seasoning. Massage them well together. There will be clumps forming but smooth them out the best you can on in the bag.
On a sheet pan, lay out the chicken thighs about 2 inches apart. If you notice any stubborn clumps when you pull them from the bag now is the time to spread the seasoning over the thigh.
Place in the oven and bake for 30 minutes. Check at 30 minutes to make sure nothing is burning. Add another 15 minutes and make sure the skin is crispy at the top before you pull them from the oven.
Allow them to cool a bit then serve.