Absolutely no indication of the push to talk key?

[Deckchair]

Hey, new to this game (enjoying it so far), and I've been playing local games for a little while but decided to delve into the multiplayer a bit, yet I find myself unable to respond to people because the options>controls seem to display seemingly no indication of what the push to talk key is? The only keys I saw that could have had any effect listed were the callout key (c) and the hold to talk key (L alt) perhaps I'm doing something wrong but neither of those had the desired effect. I assumed the L alt key was for voice chat, and the callout key to be like a strobe, or indication for something, I tried both anyway and neither seemd to function for chat.

But even if I am wrong and it is one of these listed here, you'd think it could have been made a bit more clear? it would be easily misinterpreted.

Anyway if you could help it would be appreciated.

[AnsonMyPants]

F1 will open chat history, which you can talk in. and Tab will also let you talk type into