Do I get reputation points for it? is there a specific procedure?
Once a site has been launched there isn't a way, nor is there any reputation for doing so.
If you refer someone during the Area 51 phase then there are badges and a 25 point reputation bonus for your Area 51 profile:
Referred user with a confirmed email address follows through on their commitment +25
You also get Area 51 badges for referring other users:
- Activist (gold) Referred 100 committers to a proposal
- Campaigner (silver) Referred 25 committers to a proposal
- Lobbyist (bronze) First commitment referral
- Promoter (bronze) Referred 5 committers to a proposal