Step #4. Choose your paper path
There are three paper paths (not including the roll-feed), and all work well. I recommend using the tray whenever possible because it is easy to adjust for different size papers, and multiple prints can be made without babysitting the machine. The front path can be used for sheets up to 18x63.9 inches (possibly longer with a RIP), and the rear path should be reserved for heavy sheets and other materials, also up to 18x63.9 inches.
Step #5. Get printing!
After plugging in the appropriate profile in the File>Print with Preview screen, press Print, which will bring up the dialog box below. The paper type selected should match the paper you are using. Also remember to choose "Application Managed Color" in the Print Dialog (right) when using a custom or HP-supplied profile.
When choosing a paper for the HP Designjet 90, it is important to note that "swellable" inkjet papers will offer greater longevity on HP Designjet printers, compared with virtually all other paper types.