A Plus Letter,
Put an image box on your page, then right-click on it to access it's expression editor. You can then use conditions for the file name and path, and incorporate fields. Example:
IF([Region] = "A", "C:\files\RegionA.pdf", "C:\files\RegionB.pdf")
This will make a comparison on the [Region] field, and load either the pdf RegionA or RegionB. Another example:
IF([ID] = "1", "C:\files\" & [PDFName] & ".pdf", "C:\files\default.pdf")
In this case, if the [ID] field is equal to 1, it will load the pdf with the name contained in the [PDFName] field. Since that name doesn't include the extension, we concatenate it. If [ID] isn't equal to 1, we load default.pdf.
These are just some examples on how you can do it, but that should give you a good start for your own situation.
Hope that helps!
Regards,
Raphaƫl Lalonde Lefebvre