Certainly do not apply the recommended dosages stated in the directions, that will most likely be too strong and you may overdose the fish. Most manufactures of medication do list their telephone numbers on the package, and once you have identified which medication to use you could contact them for this dosage. What I can tell you is how to apply the medication to the food. Using the smallest amount of freshwater possible mix the medication into the freshwater. Too much water and the food becomes runny and difficult to handle.
Most foods contain some salt.
The salt in the food will draw up the medicated freshwater much more readily. Because the fish are now consuming the food directly the impact of the medication is much more effective. Additionally, the cost of medication is lower since you have now used less.