Am I feeding my cats enough?

I feed my two cats a whole bowl of dry Purina "Seafood Sensations" every morning. Then I give them a small can of Friskies "Special Diet" at night. The one cat is skinny and is always waiting by the kitchen for the wet food like hours before I feed them it which is around 8pm every day as if he's expecting it at least twice a day. Should I be feeding them more?