Facebook allows you to have a custom "Follow" action, but they don't make it obvious... for obvious reasons.
- Create a custom action with a name other than
follow
- On the next page, change the name to
follow
This is not sneaky in any way. After being rejected several times for synonymous actions like "track" and "subscribe" to try to work around the implied no-custom-follows limitation, it was finally suggested to me by the reviewer that I use the word "follow" for my custom action.