i'm type of tied to an apache server.

I've different subdomains

http://suba.host.com
http://subb.host.com
http://subc.host.com

How do i create an htaccess rule that can help me mask the actual address?

http://app.host.com/myurl/php/

Right now i've got a RewriteRule rule, however i dont want the customers to determine the actual address.

All of the subdomains indicate exactly the same application. I load another profile based on the source.

Just tips!