I have a problem with
page sizes not being right when printing letter/A4 pages to PDF from Word and Excel.
When I select the printer driver properties as ANSI A, and the Excel properties as Letter, the PDF is produced as an A4 document.
In Word and Excel there is a "Scale content for A4 or 8.5 x 11'' paper sizes" function, with this enabled Word and Excel will always force A4 or Letter based on your regional settings (e.g. A4 for Europe Letter for the US).
In either program on the File tab click Options and navigate to the Advanced category.
Scroll to the Print section and uncheck the option Scale content for A4 or 8.5 x 11" paper sizes.
You should now find the paper size outputs correctly from this program.
Note that you may have to do this individually with each Microsoft Office product.