Hi,
If you don't need to keep the link between the dft file and the 3D file (psm) and also don't need an intelligent pattern which can be modified; then, you can just right click on you flat pattern view, choose 'convert to 2D view' the double-click on that view (or RMB/draw in view) select the flat and click the rectangular pattern command. Then save as dxf.
If you need to keep the link and also need a smart pattern, you can do the following: create another psm or par file, use insert/part copy to incorporate the flat pattern in that file. Create an assembly (nesting) with that file or a bunch of flat files; you can also use pattern parts (based on an assembly sketch that contains a pattern) to repeat and position your flats in the nesting. Then create a dft with a top view of that asm (scale 1:1 or draw in view) followed by save as dxf.
HTH,
Fred