Royale Canin would not be on my list of preferred dog foods, but if you're comfortable with it...
Rather than canned as a supplement, think of real meat. Here's something for you to consider. Here is some nutritional information for cooked chicken thigh (you'll find a more detailed analysis on this site: http://www.nutritiondata.com/facts/p...products/722/2
Vitamin E (Alpha Tocopherol)
All these vitamins and minerals are found naturally in chicken, not added in as supplements and no artificial preservatives needed
. Something you're not likely to find in any commercial dog food. Doesn't it make more sense to feed the real thing if you're looking to supplement?