not sure what you are trying to do
but ssd1306_18.inc is needed for pic 18 along with font7x5_18.bas
that system is a "light version" it has a fixed 5x7 width, the only way to change the font size is to alter the include


the other version "grx.pbpmod" is more generic, pic18 only and uses variable width fonts and has drivers for multiple display types