Open the top of the sprayer, and make sure any old residue is cleaned out. A simple wash with water will clean out any existing debris.
Pour water into the tank with a hose. Keep note of how many gallons your sprayer holds.
Pour the concentrate into the tank. For most residential jobs, you will need to add 2 ounces of Roundup Pro for each gallon of water.
Close the top of the sprayer and shake it to mix the water and Roundup Pro concentrate.