Press space :D Edit from future self: F4F can be okay if someone says they're okay with it, or if you ask nicely instead of being rude (like in my badly drawn example). I personally don't do it because I want to get followers because they respect/admire me (or if they're my friends), but I think if you want to do it than just be respectful.
I made this project so you can learn what f4f is and why you shouldn't do it!