Linkrel & Custom Post Meta

Hi guys,
I want to add prerender and prefetch to the footer.php and these links depend on which page is being loaded.So the prerender/prefetch links are chosen individually from particular page/post

So far I have figure what to put in footer.php and my theme metaboxes.php file

footer.php:

$link_prefetch = (get_post_meta($id, ‘link_prefetch’, true) !== ” ? get_post_meta($id, ‘link_prefetch’, true) : false);

<link rel=”prefetch” href=”<?php echo $link_prefetch ; ?>”>

and

$link_prerender = (get_post_meta($id, ‘link_prerender’, true) !== ” ? get_post_meta($id, ‘link_prerender’, true) : false);

<link rel=”prefetch” href=”<?php echo $link_prerender ; ?>”>

metaboxes.php:

array(
‘label’ => ‘Link Rel Prefetch’,
‘id’ => ‘link_rel_prefetch’,
‘type’ => ‘list-item’,
‘settings’ => array(
array(
‘label’ => ‘Link Prefetch’,
‘id’ => ‘link_prefetch’,
‘type’ => ‘page_select’,
),
)
)

The only thing is I don’t know how to write the proper php line to make it keep adding new link_rel to the footer.php as I add more in each page via post meta.