no no no lol. F12 through Steam will only take a screenshot of what's on the screen at the moment you press it. It won't generate a picture of the whole farm. If you just want what's on screen, then sure, F12 is fine. But if you want the whole farm in your shot, you have to go through the menu for it, there is no hot key. As for F4, it's meant as a tool for screenshots with F12 by getting rid of the GUI overlay(the toolbar, and the date/time/money panel up in the top right corner).
Perhaps u/ConcernedApe could add a hotkey for taking a shot of the whole farm when/if there is another update?