<resource name="font" type="font" filename="RobotoRegular.ttf" size="18" />
<resource name="font_sm" type="font" filename="RobotoRegular.ttf" size="18" />
If notice, I used a .ttf font in this theme because you can set the size as needed. In this case they are set to 18. TWRP has to support this feature for this font method to work in this theme. As of 220.127.116.11, TWRP supports ttf fonts. This theme is based on 18.104.22.168, but I have tested it on 22.214.171.124 and saw nothing unusual stand out to me. Should work between 126.96.36.199-188.8.131.52. I wouldn't bother using it any higher than stated. Other than that, the theme should work great on any 480x800 device.