index.php

<?php
/**
 * Generar un sitemap con PHP y Sitemap.php
 * 
 * @author parzibyte
 */
# Incluye clase, o autoloader
include_once "Sitemap.php";
# Indica que vas a usar el namespace
use SitemapPHP\Sitemap;
# Crear sitemap
$sitemap = new Sitemap("https://parzibyte.me");

# Agrega todas las URL
$sitemap->addItem("/", "1.0", "yearly", "Today");
$sitemap->addItem("/blog", "0.9", "daily", "Today");
$sitemap->addItem("/apps/cotizaciones", "0.9", "daily", "Today");
# Genera el sitemap
$sitemap->createSitemapIndex("https://parzibyte.me/", "Today");

sitemap-index.xml

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
 <sitemap>
  <loc>https://parzibyte.me/sitemap.xml</loc>
  <lastmod>2019-03-23</lastmod>
 </sitemap>
</sitemapindex>

sitemap.xml

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
 <url>
  <loc>https://parzibyte.me/</loc>
  <priority>1.0</priority>
  <changefreq>yearly</changefreq>
  <lastmod>2019-03-23</lastmod>
 </url>
 <url>
  <loc>https://parzibyte.me/blog</loc>
  <priority>0.9</priority>
  <changefreq>daily</changefreq>
  <lastmod>2019-03-23</lastmod>
 </url>
</urlset>