Host github.com
    IdentityFile ~/.ssh/your_github_cert_rsa
    UseKeychain yes

Host *
    UseKeychain yes

UseKeychain

             On macOS, specifies whether the system should search for
             passphrases in the user's keychain when attempting to use a par-
             ticular key. When the passphrase is provided by the user, this
             option also specifies whether the passphrase should be stored
             into the keychain once it has been verified to be correct.  The
             argument must be ``yes'' or ``no''.  The default is ``no''.

KeychainIntegration
  Specifies whether to enable Keychain support on Mac OS X.
  If Keychain support is enabled, then passwords for identities can be
  managed via the Mac OS X Keychain.
  The value for this keyword must be ``yes'' or ``no''.  The default is ``yes''.
AskPassGUI
  Show the system password prompt