How to flatten a PDF using Acrobat in a PDF reader — the best PDF Reader in Apple Mac Tips for using an app like the Adobe Acrobat Reader to flatten and manage the PDF. The Adobe Acrobat user guide states: Many users like the Adobe Acrobat app, which allows them to use text manipulation software like Microsoft Word or Illustrator. Adobe Acrobat also comes with a few options that are particularly useful for flatterers: Automatic Page Size Calculation — If you have a PDF with large text or complex symbols or graphs, you will need to manually adjust the size of the PDF. Acrobat Classic allows one to adjust the document size. If you know how to use the PDF reader application, you can adjust the document size Adobe Acrobat Reader for Mac and PC — Mac and PC Adobe Acrobat Pro DC allows one to adjust the document size so users of PDF-optimized versions of word, graph, and presentation software can apply changes automatically on the fly.