Based on my understanding, you create and deploy a report to report server, but you comes an issue when you export the report to PDF from report server, right?
In Reporting Services, the PDF renderer is a physical page renderer. For this renderer, it's important to keep in mind the concept of Usable Area. The Usable Area is the amount of space left on a page for your report to be drawn after reserving space for
margins, headers and footers, and column spacing (for multi-column reports).
Horizontal usable area:
X = Page.Width - (Left Margin + Right Margin)
Vertical usable area:
Y = Page.Height - (Top Margin + Bottom Margin + Header Height + Footer Height)
Besides, since Print Layout is also a physical page renderer, we could preview the report in SSDT or BIDS in Print Layout mode to check if the report display well. If the report render fine in this mode then deploy it to report server, it should not come
across an issue when exporting to PDF.
Pagination in Reporting Services (Report Builder and SSRS)
Exporting to a PDF File
If you have any question, please feel free to ask.