I was recently setting up a reporting server running in sharepoint integarted mode connected to an existing farm. After installing SQL 2012 in SharePoint integrated mode I executed following commands (Install-SPRSService, Install-SPRSServiceProxy) to setup the reporting shared service in sharepoint. The command executed successfully but i was unable to see SQL Server Reporting Services Service under system settings in Central Admin. I went through the sharepoint logs and couldn't find anything in there. NO ERRORS. After spending a lot of time i figured out the solution.
SOLUTION: