SSH keys setup on Mac OsX

To add multiple ssh keys to your system, you need to edit config file ~/.ssh/config and put lines like below, this will also help store password for your ssh in keychain and use agent forwarding so you can use your keys on virtual machines like vagrant

Host *
  UseKeychain yes
  AddKeysToAgent yes
  ForwardAgent yes
  IdentityFile ~/.ssh/id_rsa
  IdentityFile ~/.ssh/marbl

more on that here