Please note that unlike fonts, Keyboard Drivers are suitable for one language only, for example if you wish to type in Polish and Czech, you can use the same Central European (Latin 2) font, but you need two different Keyboard Drivers.
If you do not have a Keyboard Driver, you can enter the foreign letters by typing their codes on the numeric pad while the <Alt> key is held down, or by importing them from an application such as !Chars or (even better) !XChars.
Risc PC and the older Archimedes have different keyboards from each other, therefore a different Keyboard Drivers is needed.