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:
- 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.
- Under "Discard Objects," check "Detect and merge image fragments."
- 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: