Question: My website has images that are hosted outside my Root URL on a CDN (Content Delivery Network). Can Sitemap Creator include these images in my sitemap?
Answer: Yes, just include the hostname of your CDN (with the “http://” prefix) as an Additional Root URL (in Advanced Project Settings). This will tell Sitemap Creator that you want to include content located on the CDN in your sitemap.
Remember that you must verify your CDN in your Google Webmaster Tools account before Google will accept the images.