Was my first flock, didn't know until I slaughtered a cockerel and it was covered in lice.
Never had mites tho(knock wood)....but have never gotten new birds other than hatching from my flock or day olds from farm stores.
This says it's 1.0% permethrin....the stuff most of us use here is Gordons 10(10.0% permethrin)
I dilute the Gordons at 5 mls (one teaspoons) per 1/4 gallon(1qts) of water in the sprayer.
More math than I can figure, but maybe you(or your vet) can do it.