The Buyers Agency form speaks about commissions collected helping a Buyer buy AND...a Renter renting. You bet your Realtor can assist you with leasing!!
Now your agent is not going to make a lot of money on a lease, but if they want to keep you for a client (your going to rent now...buy later???!!), then I would think they can assist you. Private rentals are listed with Realtors via our MLS and real estate portals like Trulia and we also have apartment services to help you find something short term. The key is to speak to your Realtor.
Now, all that said. If you want to do this yourself (and it will take you longer) or you simply do not want to work with this person, let them know you wish to terminate the agreement. You may be required to pay some marketing fees, but likely you won't. Just get something in writing from the agent's Broker (their boss) saying your agreement is no longer valid. I hope it can work out with your current Realtor as you already have been working together on the sale. Good luck!
Mark McNitt, Bernstein Realty