While there is no law to make it compulsory to sign the authorization to sell/rent form, we advised our clients to sign as you will know who you have given the rights to market your property. There are a lot of fake agents and brokers in the market whom might be using your property to scam others. With the signed authorization, you can protect yourself from the potential troubles. Besides, you will have a documented terms and conditions, fees payable to agency and other important information in the form. A little advise, make sure you read and understand the content before signing, especially to know the difference between an exclusive appointment and a general appointment.