rcp_metabox_post_types

Note: This is part of the developer docs and is considered custom code.
Unfortunately, we cannot provide support for custom code at this time as we do not have the additional resources that would be necessary to provide support for custom code.

If you need assistance with this, please reach out to our list of consultants for further assistance:
https://codeable.io/developers/restrict-content-pro/

By default, the "restrict this content" meta box is added to all public post types. There may be some instances where you want to add the meta box to another post type, and this filter makes it very simple. All you have to do is add your post type to the array, like so:

function ag_rcp_metabox_post_types( $post_types ) {
    $post_types[] = 'post_type_name';

    return $post_types;
}

add_filter( 'rcp_metabox_post_types', 'ag_rcp_metabox_post_types' );