I am glad you like my library.
The small font was taken directly from the library made by ITead, so I do not know how it was made.
When making the large font I did actually calculate all the values manually
Due to the limited memory on the Arduino, I would not recommend adding another font, but feel free to replace the exitsting ones.
If you require other sizes than 8x12 or 16x16 you will have to make alteration to the print-functions as well.
If you need help with the format of the files/arrays, please let me know.