Tested this and it worked perfectly on Genesis.
You can also use HTML tags in the custom field.
add_action( 'genesis_entry_header', 'content_after_archive_title', 15 );
function content_after_archive_title() {
if ( is_home() && genesis_get_custom_field('after-title') ) :
echo '<div class="after-title">'. genesis_get_custom_field('after-title') .'</div>';
endif;
}
Uses the native custom fields meta box which you can reposition under the Editor.
You could also hand code a meta box for this using the edit_form_after_title hook if you want the box before the editor or use a plugin like ACF.
If your theme doesn’t include a hook for the title or post info meta, you could use the content or post meta filter or action hook instead.
Change Position: If you want it before the post info, simply change the 3rd parameter to 11 and here’s the result:
