Check out my collection of Multiboard Models here!
This model is a simple guide to ensure the filament goes directly from the spool all the way to the printer head. I am no longer using the printer's mount point (but the PTFE tube size was ok so I kept it.
I use the black fitting where the PTFE tube goes completely through the fitting and exits the other end. Push it until it's flush with the exit hole on the other side. If you only have a blue fitting, then the PTFE tube stops at the fitting and you may one day find out that friction ate through a bit of the holder's exit hole. IF this really bothers you, use the Fusion360 file attached to edit a remake, or send me a note and i'll work it up.
It's a nice addition to the spool holder here: Multiboard Spool Holder