The dose of mt2 depends on your body weight,This is example for average 70kg adult 0.25mg-very light 0.5mg-light 1mg-common standard 1.5-strong 2mg-very strong .

Accourding to this ,100kg male can take 1.5-2mg as a weekly dose,and 50kg female should start off with 0.25mg to be safe and then move to 0.5mg and 1mg if needed, pre-loading dose is 2x or 3x smaller than your normal maintenance dose.Reminder ,you dont need to do this unless your are in rush to get really dark in a matter of days.
Melanotan is dose-dependant. that means more you use,darker your skin tone will be.But there's no need to overdo it.