You do not need any field to chart this data as you can specify a calculation as the source of data for your "wedge" data. But you'll need at least two wedges and this won't be data where you can use the "found Set" data source option.
Select the "delimited data" data source option.
And specify the calculation option for your category labels and slice data.
Your category labels calc can be: List ( "found" ; "Omitted" )
Your Slice Data calc can be: List ( Get ( FoundCount ) ; Get ( TotalRecordCount ) - Get ( FoundCount ) )
Works perfectly! But on my layout in browse mode, the graph itself is a puny size relative to the field size. I have set padding to zero for all sides, top and bottom. Other than the pie chart itself, I have no text, legends, etc. How I can get the chart to fill the area?
Unfortunately, that is a known limitation to chart objects in FileMaker. You'd have to either find a way to make that work by modifying your layout design or use a different tool to chart your data--such as Java in a web viewer or a plug in that offers different charting options than the build in tool.