I see this has been addressed before, such as http://formidablepro.com/help-desk/adding-default-website-address-from-user-data/ but it looks like this was for a previous version of the registration addon?
I can’t figure out how to send the web address field to the website field already in WP. I have added the user meta field “user_url” as shown in the screenshot.
A related question: would there be a way to add the http:// prefix automatically so that users won’t get an error if they delete it from the field? (I usually tab through forms which highlights the default value and overwrites it when I go to type).