These two quotes make it clear
just to clarify... i am allowed to put my ref link in my signature and suggest users use it in my main post?
Do not make topics or replies just to share your referral link. Whether it's in your sig, avatar, personal message, profile, within the post itself, or tattooed on your forehead is irrelevant.
Edited for clarity.
You are allowed to put your refferal link on your signature
So, when you make promotion, ask users to join through refferal link on your signature
And you might want to use link shortener, so every user can't know the refferal link
Any you should know it already when you join this forum
Still referral spam.
If you pay people to register under your ref link it works on games and rounds, also sometimes when people find new promos or giveaways they give their ref link and a non ref link, seems to be allowed aswell.
Still referral spam.
There is a similar thread here:
https://bitcointalk.org/index.php?topic=1236568.0