[jackie_w]

Hi MarkoRamius,

Welcome to MobileRead

Although Kobo makes it very easy to load your own fonts there are a few strict rules about filenames and internal font metrics for them to work properly. You may already have done items 1 and 2 but you may not be aware of item 3.

1. The Amazon firmware contains a lot of Ember font files. Make sure you pick a matched set of 4. I suspect the 4 you need all have an internal font name of Amazon Ember (not Amazon Ember Medium or Amazon Ember Bold or Amazon Ember Heavy). The 4 original filenames are:
   

   Amazon-Ember-Bold.ttf
   Amazon-Ember-BoldItalic.ttf
   Amazon-Ember-Regular.ttf
   Amazon-Ember-RegularItalic.ttf

2. Kobos have a strict file naming convention. The first part of the filename needs to match exactly the internal font name of Amazon Ember (not Amazon-Ember). For this particular font, the second part of the italic filename,
   -RegularItalic, needs to be replaced with -Italic. So rename as follows:
   

   Amazon-Ember-Bold.ttf           --> Amazon Ember-Bold.ttf
   Amazon-Ember-BoldItalic.ttf     --> Amazon Ember-BoldItalic.ttf
   Amazon-Ember-Regular.ttf        --> Amazon Ember-Regular.ttf
   Amazon-Ember-RegularItalic.ttf  --> Amazon Ember-Italic.ttf

3. Unfortunately, this one is more complicated. Kobos don't like the Panose Weight font metric Amazon use inside some of their fonts. This needs to be manually corrected with a font editor utility, e.g. FontForge (free) or FontCreator (not free). If you have access to either of these I could give you more detail of how to manually correct the Panose Weight metric.
   
   The original Ember files are using Panose Weight values of Medium (-Regular and -Italic font files) and Demi (-Bold and -BoldItalic font files). Instead of values Medium/Demi Kobo expects values of Book/Bold respectively.

Just to prove it can work here's a screenshot of all 4 variants of Amazon Ember being used correctly in a kepub.