What is the recommended amount per lb?

That would depend completely on what you're working with. The amount you need in a rotary tumbler would be different than a vibratory tumbler, and would vary as well if you were using a vibrating lap. In a rotary tumbler you would need about 1.5 tablespoons of polish per pound. For a vibratory it takes about 3 ounces of polish in an 3 quart tumbler, and 4 ounces for a 6 quart. With a vibrating lap you can start with about 2 tablespoons of polish, but you may need to add more depending on the size of your lap.