The following HTML should generate a table with width of 600px:

<table width="25px" border="1px solid black">
<tr>
<td>
<table width="600">
<tbody>
<tr><td >Test</td></tr>
</tbody>
</table>
</td>
</tr>
</table>


 When the same html is imported in RadRichTextBox, the table is 25px wide.