Open Firefox options (Or preferences for MAC) .Click on "Privacy and Security". (Vie privée et sécurité)
Go all the way down to "Certificates".(Certificats)Click on "Security Devices...". (Périphériques de sécurité...)
If "Belgium eID PKCS#11 Module" is present on the left you do not need to continue this procedure.Otherwise, click "Load". (Charger)
Indicate "Belgium eID PKCS#11 Module" in the module name.Specify "beid_ff_pkcs11.dll" in the module filename.Click on "OK".
The module "Belgium eID PKCS#11 Module" now appears in the left menu.Your browser is now correctly configured to read your eID card.