New order notification email change

I was able to add the custom field using the following code:

function render_product_description($item_id, $item, $order){
    $_product = $order->get_product_from_item( $item );
    echo '<p><strong>Ref #:</strong> '.get_field( "ref", $_product->id).'</p>';
}
add_action('woocommerce_order_item_meta_end', 'render_product_description',10,3);