The product label for Drexel AMS Supreme states: 2.5 gallons of this product per 100 gallons of spray solution (2.5% v/v) will provide 8.5 pounds of dry ammonium sulfate equivalent plus the optimum level (8 ounces) of HPG polymer technology.
This breaks down to approx 3.2 oz per gallon of water
Drexel AMS Supreme is a surfactant that is intended to be used with a post-emergent herbicide. No need to use it with a pre-emergent such as Prodamine WDG.