I spray a magnesium solution (think magnesium oil diluted with water) into my pits after a shower. I think it works much like rubbing a salt crystal in terms of smacking down odors, and I believe that I'm picking up transdermal magnesium at the same time.
I kept it simple and off-the-shelf, my local healthfood store had this in stock and I just pour this into a mister undiluted. http://www.swansonvitamins.com/CRR008/ItemDetail
The magnesium chloride and magnesium acetate mix is what appealed to me, i suspect that a mix of organic and inorganic magnesium salts helps make sure that I can absorb AMAP.