Rhino Pdf export vector seems not to work

I am trying to print a few drawings (from layout) with Rhino PDF but the lines in the final pdf appear not to be vectors but instead seem to have low resolution and have artefacts. See images below. Any suggestion on how to improve this?

settings:

Resulting pdf:

Hi Vincenzo -
When you print with vector output from a layout, the objects that are on the layout will be in the vector format. Objects that you see in the details will depend on the display mode that is used in those details. If those are not wireframe or the objects are not curves and hatches, the result will be raster images in those details. You’ll have to use the Make2D command to ensure curves, and thus vectors, in those cases.
-wim