You can insert a PDF file as a reference model in your Tekla Structures model. During import, Tekla Structures converts the PDF into the DXF format.
Insert a PDF file in a model
Limitations
Only vector graphics are converted, not raster graphics.
Warning:
The PDF document might be subject to minor scaling adjustments during the printing process to make it fit a standard page size. That means that it may not be 100% accurate in all directions once scaled to full size.