I use just a float valve, but then you need to gravity feed from a storage container, you can go from your RODI right to your float valve, but it will cause your RODI to cycle on an off like crazy.
You need something with a high low switch....or something to limit how often the RODI system can run. Some folks will run the RODI system once or twice a day.......and then let it shut off when the float switch stops the flow.
The loc line system just has an extra solenoid valve and a float switch. That is easy to DIY, just mount a float switch, get a solenoid valve.
(Here is an example
http://www.buckeyehydro.com/solenoid-valve-1-4-inch-24-vac/ and then a power supply. Just make sure to make waterproof electrical connections.