I just printed out a PDF I created in Quark and sure enough, it is smaller than the original file. In my case it reduced itself to 93% of the original..
I have been using Quark to create PDF's of ads that I have been sending to publications. I haven't noticed that they are smaller than the space they are supposed to fit in. I will have to check that. Possibly the publications have been enlarging them to fit....assuming that's even possible.
Just to review how to make a PDF in Quark, since some of the previous explanations might not be clear to the neophyte, do this:
File>Export>Layout as PDF
When window opens, click on button called 'Options' that is in the bottom portion of the window. Then you get a window with several boxes across the top that lets you configure....and compress...your file into whatever type and size of pdf you want.
However, how to get around the size reduction is a mystery.