The AAFCO recommended dose of Vitamin A for dogs is 100-200 IU/kg/day. Vitamin A doses vary from brand to brand of CLO, but Carlson's is about 800 IU per tsp, which would be the dose for a 50 lb dog. However, if your dog is eating liver and other good sources of A, you would need to be more worried about the total dose they are getting in a day. I guess that's why I haven't supplemented Buddy's food with A as long as he's getting 10% organ meat each day.
There's a very interesting article about CLO, Vitamin A & D and doses for humans at
http://chetday.com/codliveroilvitamindcouncil.htm .