Implement the Query rowLimit parameter:

<RSSharePointList xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xmlns:xsd=”http://www.w3.org/2001/XMLSchema“>
  <ListName>Help Desk Requests</ListName>
<Query>
<Parameters>
    <Parameter Name=”rowLimit”>
        <DefaultValue>9999</DefaultValue>
    </Parameter>  
</Parameters>
</Query>
 <ViewFields>
    <FieldRef Name=”Title” />
   </ViewFields>
</RSSharePointList>