On the basis that one supplier has one price list, you can set up a container field to hold the PDF.
Add this field to the layout you wish to have it appear on and make sure it's the correct size to be able to read.
On the Inspector, Data>>>Optimize for>>>Interactice contect (PDF etc) & start playback automatically.
This should make the PDF appear when you flick through the supplier records.
If you want this on a button, do everything above but create a large enough popover first and put the container field in the popover.
Thanks for your help Stu412.
I'm quite new to FM so can I ask what you mean by a popover?
While editing a layout, if you goto Insert>>>Popover Button, this will add a button and show an open popover on the screen which can be resized. It's a function designed to show more information without blinding the user with detail when they first land on the layout. They're used a lot on iPad layouts due to the smaller screen size, but they've got a place on desktops as well.
The user clicks the button, the popover appears (think of it as a pop-up if that helps translate!) and they should be able to view the PDF.