Welcome to the Javaranch, John!
You don't.
JSF h:form elements have to be rendered and read by JSF. They contain additional meta-data not found in ordinary HTML forms.
What you
can do is post PHP to a non-JSF URL in your webapp such as a REST processor or a
servlet that then stores the incoming form data in a session-scope javabean. That javabean can then be referenced by JSF as a managed object.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.