Some of the Rentals do go through Realtors and we charge a percentage of the years rent. In exchange for that we advertise, screen (credit), negotiate and collect the initial payment for the tenant.(first and security).
I do recommend that you subscribe to additional screening services that most Realtors do not have such as criminal background checks to be safe.
Some landlords prefer to use a Rental Service and advertise there. Some landlord use professional property management. Property managers will help you maintain the property and handle leasing.