Since they neglected to tell you to create the XML file in a full format here is the result...
I think...
<?xml version="1.0" encoding="utf-8" ?>
<ItemMetadata>
<z:row xmlns:z="#RowsetSchema" />
<z:row xmlns:z="#RowsetSchema" ows_instructions="" />
</ItemMetadata>
Anyway, the designer would throw xml errors and be generally pissy with just those two elements.