Are there particular vitamins that your cat isn't getting enough of? One reason it may be hard to find one that doesn't have oil in it is because some vitamins are fat-soluble and the oil would be needed for the cat to absorb them. I gave my cat Pet-Tinic for a while to boost his immune system (under my vet's advice). It has meat flavoring but the first ingredients are corn syrup and water. Pfizer has more information at www.pfizerah.com
. This site has good information about vitamins (such as which ones are fat-soluble), even though it includes commercial links: http://www.petcaretips.net/pet_vitamin_supplements.html
. If none of that works for you, you could get solid vitamin tablets and a pill crusher, and mix the resulting powder into the canned chicken juice. Again, I woudl check with your vet if you haven't already before you start supplementing your cat's diet.