Hi Krishnan,
RF Toolbox wont be visible in Simulink Library Browser, it is mainly the MATLAB environment.
I think you wanted to use Simulink blocks of RF Blockset. Can you install RF Blockset and observe if you have got what is required? Here are the recommended products for RF Toolbox.
Once the installation has made for RF Blockset, you can observe the blocks of Circuit Envelope, Equivalent Baseband and Idealized baseband.
Hope this helps.
Thanking you.
Regards,
Sriram