views_test_rss.module

<?php

/**
 * @file
 * Hook implementations for this module.
 */

/**
 * Implements hook_preprocess_HOOK().
 */
function views_test_rss_preprocess_views_view_rss(&$variables) {
  $variables['channel_elements'][] = [
    '#type' => 'html_tag',
    '#tag' => 'copyright',
    '#value' => t('Copyright 2019 Dries Buytaert'),
  ];
}