Using a " generic " brand of Glysophate I would use ammonium sulfate regardless. When we do applications of the generic roundup we always add about 1 gallon to 400 gallons of a ammonium sulfate liquid. In a smaller amount I would still use about that same figure, a 1/4% ( which is 1 gallon per 400 gallons water) so a quart would be the correct figure for 100gallons, a pint per 50gallons of water and about 10oz per 30 gallons of water. You can figure about .32 ounces per gallon of water. AND like stated before add the sulfate before the glysophate. I would also reccomend using dawn dish soap as a surfactant if using generic roundup. In a 30 gallon tank I would use about 4-6 oz per 30 gallon tank. If you use more, its not going to hurt.
If you have woody brush or vines, like previously stated add 2,4-D with the mix. About 3/4 of a ounce to a ounce per gallon of water should do very well. So if you have a 30 gallon tank 22.5 to 32 ounces. About the same on the roundup.
I would recommend using actual Roundup ( Original Max or Power Max). Its a little more expensive, but as a aerial applicator and on our family farm we have used both the generic and the " real " Roundup. Generic is cheaper, but it takes longer to work and does not seem to " hold " as long as the real stuff.
Any questions about chemicals you can PM me and I can help you out!