If you are not using a preference centre then the unsubscribe link is the same for all messages and profiles. The URL to use for the unsubscribe link is:
http://{~customDomain~}/_act/get_rcr.php?{~mailId~}Note that this link will not work on a test send and will only be valid on a live campaign.
If you're using a preference centre then you'll need to use a unique link for each profile, please get in touch if you're unsure what this is.