Important: This is no longer required! The theme does this automatically now.
add_action( 'wp_head', function() {
$ticons_dir = get_template_directory_uri() . '/assets/lib/ticons/fonts/';
echo '<link rel="preload" href="' . $ticons_dir . 'ticons.woff2" as="font" type="font/woff2" crossorigin>';
echo '<link rel="preload" href="' . $ticons_dir . 'ticons.woff" as="font" type="font/woff2" crossorigin>';
} );