How to customise Quote Template

I would like to add custom fields (lookup relationship fields) to the Quote Line Items section, 

I first added them the lookup relationship fields to the Quote Line Items and added them after to the tempplate in the Quote Line Items section.

When I click Save and Preview, everything is ok but when I go back to Quote and create pdf, the custom fields I added to the Quote Line Items section don't show at all.

Please, I would be grateful if someone could help with it.

Thanks