In order to be eligible to make a sworn or affirmed statement you have to be at least 12 years of age; those under the age of 12 must be accompanied by a parent, guardian or carer. There are no costs for making a sworn statement. Sworn statements can be made at the Department of Civil Affairs (burgerzaken) of a City Office (stadsloket). Make an appointment in advance, and if necessary an interpreter can be arranged. Bring all official documents in your possession.
From outside the Netherlands
If you wish to take up residence in the Netherlands from abroad you first have to register with the Civil Registry (Basisinformatie), Immigration and Nationalities Division (Afdeling Immigratie en Nationaliteiten). For that purpose, you need to make an appointment by phone. When making the appointment indicate that you do not have any source documents. A sworn statement will then be taken from you at the same time that you register.
Civil Registry (Basisinformatie)
Address: Jodenbreestraat 25, 1011 NH Amsterdam
Telephone: 14 020 (Monday to Friday, 8:00 to 18:00)