O.k. There it is!
Ivermectin Pour On dosage is 0.09 ml per pound of weight, applied to the base of the neck-needs to be in contact with the skin. Give once, then repeat in 14 days. So...a 5 pound hen would receive 0.45ml, your rooster weighs more than that I'm sure.
Ivermectin 1% (injectable) dosage is 0.045 ml per pound of weight, same way, apply to base of neck along the spine, needs to come into contact with the skin. Give once, then repeat in 14 days. Example a 5 pound hen would receive 0.23 ml.
The vaseline probably did help smother the SLM, but it's best to apply it a couple of times a week if possible. The scales may still look pretty bad for a good while.