To use a specific gemset using RVM make sure you have RVM installed first.

  rvm -v

If you have it installed, create a dir where to setup your new project in Rails and follow the rest of the commands:

  mkdir myapp
  cd myapp
  $ rvm gemset create [name of gemset]
  rvm --rvmrc [ruby version]@[name of gemset]
  cd ../
  cd [app dir] # To refresh the dir. On cd back to dir you will be asked if to execute the shell script. Choose Yes
  bundle install

Now you will have your project specific gemset at [email protected] (example).