It depends on how you added the custom fields. If you used a custom fields plugin, you may be able to call a plugin-specific function. For example, with ACF, you can call get_field('fieldname')
to retrieve one specific custom field.
If you’re not using ACF (or even if you are), as long as your fields are stored as postmeta, you can do something like
<?php
if(get_post_meta($post->ID, 'quality_score', true)) {
echo get_post_meta($post->ID, 'quality_score', true);
}
?>
or format more heavily, i.e.
<?php
if(get_post_meta($post->ID, 'quality_score', true)) {
$quality_score = get_post_meta($post->ID, 'quality_score', true);
echo '<div class="quality">' . $quality_score . '</div>';
}
?>