What if I already have a PDF?

You can use Adobe Acrobat's optimizer tool to help your PDF to meet digital specs (in the Advanced menu of Acrobat 9 and earlier, or the File > Save menu in Acrobat 10 and higher). To do so, use the following settings:

• Compatible with Acrobat 6.X or later (set this first)
• Leave other default setting alone except for the following:
  1. Under "Fonts" (in the left-hand list), make sure all fonts are embedded. In Acrobat 9.X, there's a check box for "Do Not Unembed Any Font." Check that.
  2. Under "Discard Objects," check "Detect and merge image fragments."
  3. Under "Discard User Data," check "Discard Hidden Layer Content and Flatten Visible layers."

If you already have existing PDFs, there are a number of ways to reduce file size. We recommend you "pre-flight" the file (via the Acrobat "Print" menu) using the "Online Publishing (Optimize for Quality)" setting before you optimize the file. In general, file size is not a problem for customers until the file is larger than ~100 Mb, but the smaller a file is, of course, the quicker it will be for customers to download and use. 

For a more in-depth information:

• Here is the Digital Spec List
• Here is the Digital Checklist to double-check your work.