OK not wanting to sound contrarian over here BUT! I've tried a similar mix-of-oils-with-soda-and-essential-oils homemade thingie made by a friend and it does not really work for me. Main reason is probably I sweat more than normal esp in the armpits + I have oily skin. So adding more oil under there basically does not help.
What I've noticed is if I stop using ANY kind of product and gasp shaved my armpits gasp there's not much of a smell, if any. In case I'd like to have some nice smell rather than the regular body smell, I'd use wife's deo stick, which even if it's not the most natural thing in the world is still a very nice alternative. And also I can use it as aftershave.
You? Contrarian? NEVER!!!!
That's a bit of a fallacy about oils on oily skin. Oils are good for oily skin - stops them producing too much oil! I think the idea is with nat deo is that it helps with the good bacteria that normal, shop bought, aluminium products kills. So the less you use it the less you smell, so if you dont use any, then you're probably good.
I generally don't wear it at all unless I"m at work, because no one likes a smelly teacher!