Based on the source code it uses the Classipress theme
Classified Ads Software, WordPress Classified Theme | AppThemes .
You can add custom field for the url through the custom forms which can be done at the Classipress admin settings.
Please help our moderating team work more efficiently by not sending us support questions via PM. You can read more about how AppThemes support works
here. However, you can send a PM to follow up and remind me if I missed your support request/thread.
Thank you and have a nice day.
