How to indicate user password with "su" remote execution method

I want to know how to indicate the password when we use su method to remote execution. Is there a field like “sudo password” in hidden fields in jobs templates ?
Because i changed the value of remote_execution_effective_user in settings to “su” but i don’t understand how to indicate the password of user account.

Foreman 1.21
remoteExecution 1.7

If I recall REX supports only password-less su. Or to put it another way, sudo is the only method which supports a password