Received a letter today from Thermojet's Pitt., PA facility in response to my letter. They say that the stoves are no longer shipped with a scribed line. They suggest filling the burner 2/3 or 3/4 full, snuffing out any flame left after you have cooked whatever you need and reusing any unburned fuel. This can be done by removing the windscreen and placing the cooking pot on top of the burner for 5 or 10 seconds to kill the flame. After it has cooled, pour the unused fuel back in the storage bottle. Alternatively, you can mark the fuel bottle into four equal parts, because it holds four ounces, using the fuel bottle as your guide.
I use a platypus because I need more than four ounces, so I have marked with the point of an old protracter a line showing the one ounce level. My mark is so slight it may wear off with time, but I imagine I'll be eye-balling the right amount of fuel after a few days with the stove without much thought.