The sitemap generation process may seem a little daunting at first but it's actually quite simple, even when you're just using RapidWeaver. All you have to do is download their Sitemap Generator script. Then make a local export of your RW site (ie ~/Sites/mysite.com). The sitemap generator has 3 modes of operation, we're interested in having it generate the map based on the directory structure, so config.xml would be:
<site base_url="http://mysite.com/" store_into="/Users/filipp/sitemap.xml.gz" verbose="1">
<directory path="/Users/filipp/Sites/mysite.com" url="http://mysite.com" default_file="index.html" />
</site>
Then just run sitemap_get.py and copy the resultant sitemap.xml.gz to your hosting site's root directory. The whole idea here is to match your RW export with your site's root on the server.