Many Dutch digital forms offer the possibility to attach a formal digital signature, called 'DigiD'. To get DiGiD you must first acquire a username and a password. With these, you can sign in and submit forms digitally.
More information on DiGiD can be found on the DigiD website. On this website you can also apply for a DiGiD password and username. The explanation is in English, however the application is unfortunately only in Dutch.
A step-by-step guide to the application process in English can be found here (PDF).
If you require further information, call the city information number 14 020 (Monday to Friday, 8:00 to 18:00).