Are you referring to the new Post Type Templates feature included in 4.7?
To make a page template available to your ‘keywords’ cpt you’ll want to add a header like this to a custom page template.
/**
* Template Name: Template Name
* Template Post Type: post, page, keywords
*/
This template would be available to all posts, pages, and your keywords cpt. Here is an example of a full page template…
<?php
/**
* ACF Flexible Content template
*
* Learn more: https://codex.wordpress.org/Template_Hierarchy
*
* @package YM
* @since 1.0
* @version 1.0
*/
/**
* Template Name: Flexible Content
* Template Post Type: post, page, product, event
*/
/**
* Add landing page body class to the head
*
* @param $classes
* @return array
*/
add_filter( 'body_class', function ( $classes ) {
$classes[] = 'flexible-content-template';
return $classes;
} );
/**
* Remove entry header
*/
remove_action( 'genesis_entry_header', 'genesis_do_post_title' );
/**
* Force full width layout
*/
add_filter( 'genesis_pre_get_option_site_layout', '__genesis_return_full_width_content' );
/**
* Remove breadcrumbs
*/
remove_action( 'genesis_before_loop', 'genesis_do_breadcrumbs' );
/**
* Add ACF Flexible Content. See inc/layout.php
*
* @uses ym_flexible_content();
*/
remove_action( 'genesis_loop', 'genesis_do_loop' );
add_action( 'genesis_after_header', 'ym_flexible_content' );
genesis();
https://make.wordpress.org/core/2016/11/03/post-type-templates-in-4-7/