OK - remembered how to do it....go to Forum Preferences on your account. The signature. You MUST right-click in the window/box (like you would for copy/paste in a word document) and select "Insert/Edit". Then insert the link. A box will come up. Click save.
Some blurb will come up but click save. Then save the whole thing....let me know how you get on. BTW if you play Battlefield the following link is where I got mine from: