Feature Request - Keypress on single secondary device

Greetings I would like to be able to use a keypress on my main PC, (likely mapping one of the extended Function keys, F13-F24) to activate a keypress on a secondary PC.  An example use case would be, using Push To Talk (PTT)or activating a AutoHotKey on a secondary machine, without having to do it on all of the via the broadcast keystroke feature.  If it could work in reverse, that would be good too.  As in, I could have my Push to Talk key on my main machine, but would be able to activate it while focused on a secondary machine, hitting that key would activate the PTT on the primary device, without having to return to that device if I am focused on the other machine.

Not sure how broadly useful for other users this would be, but I am often trying to use PTT while the mouse is on a secondary device.  I could also see this being useful for other instances as well, As in I could say hitting f13 would broadcast to Machine 2 and 3, but not Machine 1, 4 and 5 if I those set up, and this could work regardless of which machine I was currently operating on. 

Hopefully this request made sense, I tend to ramble a bit.