To add multiple QueryString parameters to the ASP .NET SiteMapNode use &

<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
  <siteMapNode title="Home" description="Home" url="Default.aspx" >
    <siteMapNode title="Test Rapport" description="Test Rapport"
     url="~/Rapporten/ViewReport.aspx?rapport=test&amp;productId=1" />
  </siteMapNode>
</siteMap>