Can someone tell me about this pheromone? Can you wear only this with cologne?
No, you can wear it all on its own if you want. It has a light orange blossom scent to help it diffuse.
A cover scent might be a good idea though as TUTH will get a bit niffy towards the end of its active life without one.
TUTH is mainly Androstenone plus small amounts of steering molecules and whilst this can be good for an established partner, it will benefit from something else to knock the relentess hardon vibe off of it for wider use. Instant Shine and IO are good moderators for young guys in clubs, whilst A314/TUTH is a good mature sexual mix for people over 30.
Its not a phero to wear to work/school. Something more balanced like Ammo is better there.
I’m being naive but why can’t you use it for work, around kids, or at school?
Because it has a very overt sexual and potentially agressive signature, which may not go down very well at work - it could piss people-off, wind-up your bosses or give a creepy/overly horny impression that is quite at odds with the workplace.
Saying that, I do sometimes wear a little with some moderation on quiet days, just to shake things-up a bit. 
Similarly it may be quite unpleasant to kids and more generally, overt pheros around developing children is something nobody advises, althoug some of the lighter socials seem ok.
Wearing tuth is like walking around with your cock out. You’re sending a very clear message that you are horny and you want sex RIGHT NOW. It’s best to use it in a nightclub/bar environment or around someone you’ve been getting close to.