On my 2009 3912, you have to take the panel lose inside the storage area next to the water connections. Behind it, you should find a hose that you can simply put into the anti freeze bottle. Flip the switch in the dock and run the water at each faucet. Make sure you bypass and drain the hot water heater or you will use a lot of fluid. There are 3 valves that need to be changed to do that.