After being charged it can be set to a frequency by right clicking on T3 Launcher Control Panel if its frequency is set in 1-9999 range. After that when you right click anywhere while within range of the launchers it will set a light beam where your cursor and start a 5 second countdown visible on your screen after which missile will be launched. If used with 2 or more launchers, every other missile will be launched with 5 second delay that will not be visible as the first one to prevent mid-air collisions.
Keep in mind that designators will only work with a Launcher Control Panel T3, as they are the only ones that have a frequency option, tier of everything else is irrelevant. As with Radar Gun, accuracy is dependant on missile launcher accuracy, specifically the tier of its Launcher Support Frame.
A Laser Designator can hold a maximum of 80kJ and must be powered in order to call in a missile strike.