We just sprinkle bicarb and rub it in a bit,,, either dry or after a shower. Works wonderfully, and the proof of that is 17yr DS who is a carpenter and used to get ewwww while going through the puberty changes. Once he switched to bicarb, no more B.O. And the wonder of it is that even when he's already a bit stinky, if we're out somewhere, the bicarb seems to take it away, not just keep it away.
Only thing is it leaves white circles on dark clothes. They wash out, but look awful when you're wearing them.
So, I'm watching here with interest to see what to use with dark clothes. The crystal ones just don't seem to last on me.
Also I've been reading in the news about some of the commercial brands mentioned here, that they've been found to contain carcinogens, and some of these are supposedly reputable brands that people have trusted for years. Bit scary.