The following instructions at the given link are pretty useful.
http://www.macworld.com/article/1168311/shrink_preview_files_without_ruining_image_quality.html
If you are not satisfied with results of the Reduce File Size filter (which we use to make PDFs small enough to send by e-mail, etc), follow these steps:
Go to the folder /System/Library/Filters, and open the XML file: Reduce File Size.qfilter
http://www.macworld.com/article/1168311/shrink_preview_files_without_ruining_image_quality.html
If you are not satisfied with results of the Reduce File Size filter (which we use to make PDFs small enough to send by e-mail, etc), follow these steps:
Go to the folder /System/Library/Filters, and open the XML file: Reduce File Size.qfilter
Now rename (copy) that into three files: Reduce File Size Good.qfilter, Reduce File Size Better.qfilter, and Reduce File Size Best.qfilter. Then change the parameters of each file: 0.25, 0.5 and 0.75 for Compression Quality (respectively) and 842, 1684, and 3508 for ImageSizeMax (ditto). (The first is A4-size at 72dpi, the second A4 at 144dpi, and the third A4 at 300dpi).
Finally, change the default string for the Name Key at the end of each file—which is what displays in the Export menu—to match its file name.
You will have 3 versions of PDF quality filters, when you "export" files to PDF next time.
