using hooks

Hello,

I stuck on adding custom fonts in Product Designer
Honestly i don't really know how to do it.
I've  checked documentation on site:

product_designer_fonts

and then searched via www for some info but i didn't find anything that can help me.
How to correctly use these hooks?

Firstly i wanted to purchase pro version but download button relocates me to version 1.0.32 without  custom fonts support so i couldn't make anything.

Thanks in advance, Patryk