Chapter 22 WAN Optimization, Web Cache, Explicit Proxy, and WCCP for FortiOS 5.0 : Web caching and SSL offloading : Forwarding URLs to forwarding servers and exempting web sites from web caching
  
Forwarding URLs to forwarding servers and exempting web sites from web caching
You can go to WAN Opt. & Cache > Cache > URL Match List and use the URL match list to forward URL patterns to forwarding server and create a list of URLs that are exempt from web caching.
• Forwarding URLs and URL patters to forwarding servers
• Exempting web sites from web caching