How to enable a custom post type to custom user role in WordPress

custom-user-role.php

<?php

add_action('admin_init','rpt_add_role_caps',999);
    /**
    add teachers capability
    */
    function rpt_add_role_caps() {

        // Add the roles you'd like to administer the custom post types
        $roles = array('rpt_teacher','editor','administrator');

        // Loop through each role and assign capabilities
        foreach($roles as $the_role) {    
             $role = get_role($the_role);               
             $role->add_cap( 'read' );
             $role->add_cap( 'read_course_document');
             $role->add_cap( 'edit_course_document' );
             $role->add_cap( 'edit_course_documents' );
             $role->add_cap( 'edit_published_course_documents' );
             $role->add_cap( 'publish_course_documents' );
             $role->add_cap( 'delete_published_course_documents' );
        }
        }

?>

https://wordpress.stackexchange.com/questions/290090/how-to-enable-a-custom-post-type-to-custom-user-role-in-wordpress