What are you looking for the supplement to do?
Kibble is already complete and balanced. Adding too many extra vitamins can even unbalance it and lead to problems. It is full of vitamins and minerals. There is no need to use any supplements in healthy dogs. Antioxidant supplementation is questionable at best. Pet foods contain some as it is.
PetDiets
I'd pick a good food and stick with it while forgoing extra supplements unless your vet says otherwise.
A lot of times these things are nothing more than money transfer and a way to get your money for no good reason.