Issue: Geometry in exported .dxf is very small, and the units are incorrect.
When you open a .dxf exported from TestFit, the geometry is very small, and the units are very small.
Issue
Cause
If geolocate DXF export (WGS84) is turned on, the exported file is in WGS84 latitude and longitude coordinates.
Solution
Toggle geolocate DXF export (WGS84) off to use your file coordinate system and units of measurement, or use a DXF viewer that supports geocoordinates.