The User's Autosurf URL field is used to show the member the URL they must click on to start the autosurf.

This output field has no variables.
However, there is a useful customisation worth mentioning, allowing the URL to be a hyperlink to the Autosurfing page itself

Examples:
• Standard format: <? users_autosurf_url (); ?>
  Custom 'clickable' format:
  <a href="<? users_autosurf_url (); ?>" target="_blank"><? users_autosurf_url ();?></a>