Well i think this one is solved, please take a look if you can and let me know if there is a simpler or better way to do it
//Wpsp show meta instead of content
add_action( 'wpsp_before_content','wpsp_add_custom_meta' );
function wpsp_add_custom_meta()
{
$meta = get_post_meta( get_the_ID(), 'kundcase_site_url', true );
if ( isset( $meta ) && '' !== $meta )
echo '<a class="button" href="'.$meta.'">Besök sidan</a>';
echo '<a class="button alignright" href="'.get_permalink( $id ).'">Läs Mer</a>';
}