Facebook

Refer to this link of a similar post. The first response explains how to link to facebook. http://boards.na.leagueoflegends.com/en/c/help-support/AZR65r04-connecting-to-facebook

Log In into your League client, at the bottom right click on "Add Friends", somewhere in there should say something about Facebook.

as found in another question, from another more helpful summoner

I've been trying for around two weeks now to get the feature up and running and it seems to fail continuously. I've tried to (un/re) install, use a different computer and a couple other things. No luck. Any advice?