Need help to set up an Apache proxy server for OIF.

Anyone with experience in setting up an Apache proxy server to proxy public requests to the OIF server? Currently, OIF, configured as IDP, is setup to integrate with OAM as an authentication engine. When the initiatesso URL hits the proxy server, the request is successfuly redirected to the OIF server. The username password login prompt shows up sucsessfully. However, upon entering username and password, user is taken to the Oracle Fusion Middleware homepage. Looks like it is redirecting to the root of the OIF server but could not get to the /fed/user/authnoam URI, which should then redirect the user to the resouce page.