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>