What kind of vitamin E did you buy? I've never seen it come in mg, only in IU.
Anyway, here are some general guidelines:
• 0 to 25 pounds - 100 IU
• 25 to 50 pounds - 200 IU
• 50 to 75 pounds - 400 IU
• 75 to 100 pounds - 600 IU
Salmon oil (it should be liquid) should be 1000mg per 10lbs of dog.
I feed both every day at the same time. There's no reason not to feed it every day, IMO. I feed raw and these are the only supplements I think are essential. With the grain diets commercial meats are fed today, dogs (and people) get way too many omega 6's and not enough omega 3's. It doesn't matter what you feed (unless it's solely organic, grass fed meat), you won't be feeding enough omega 3's. So I supplement with salmon oil. Salmon oil uses vitamin E in the body, and vitamin E protects the omega 3's from damage. So, IMO, they are best fed together.
Vitamin E is one of the fat soluble vitamins (vitamins A,D,E, and K). They are stored in the fat cells of animals (at least in people), and you can essentially overdose on them like you would a drug.
Hope that helps!