This actually works, it's not just an image.
To use it, you need to use WIDTH 16, then use the UPDATE function after printing text, and it will read the screen using CHKCHR and display the font on a BG layer.
This example uses the PTC character set, which just has normal ASCII, Japanese, and symbols.
By editing the GRP, you can make it have any characters you want, though. (up to 1024)
Unfortunately, 16x16 fonts are very rare; 8x16 is much more common.