You might try filing you FBAR, which if you get wrong results in criminal penalties, and which (practically) every American living overseas needs to complete each year:

https://bsaefiling.fincen.treas.gov/NoRegFBARFiler.html

then press the 'prepare' button to trigger the download servelet to get the PDF.

Preview cannot even open the file, let alone allow you to digitally sign it in the manner approved by the Treas Dept.