How to limit number of store results in grid?

How to limit number of store results in grid?

Using ExtJS 4.2 - I have an AJAX call populating the store with the entire
set of results in JSON format (using loadRawData). I now need to limit the
number of results being shown on the grid at a time. End goal is to
implement client-side paging. I've tried using pagingmemoryproxy with not
much luck.