To attach the file, browse to the EXE file you want to bind to the PDF file and click the "Open" button. Acrobat now lists this file as an attachment. To add a description, click the "Options ...

Open any PDF file, and if Preview recognizes that it contains form elements, an AutoFill Form button appears in the upper-right corner of the PDF window.

Need to add text to a PDF that doesn't support editing? No problem -- and no extra software required.