That's a common need! If the drop-down list for scale on PDF import doesn't contain the specific scale you require, you should look for an option to enter a Custom Scale value. Most professional software that imports PDFs, especially CAD or design tools, will provide a dedicated input field next to or below the scale drop-down where you can manually type in the exact scale ratio (e.g., 1:125 or 1mm=50mm) needed for accurate scaling of the imported drawing.