Johnston sets typically come in longer cardboard boxes with metal reinforced corners.
This is a New Home set - comes in a red box
This is a White Set
And this fits Demorest (only machine I've seen with the notch for the needle plate)
And this one - I'm not sure what it fits, as it does not fit any of what I've already got. It did not come with any plates, so that makes it harder to figure out.
And a few of the ruffler - yours is missing the screw and shirrer - that gets removed to use the ruffler with the bed mount shirr plate (slide).
The one you have looks like the Demorest or "unknown", and it could be something different too. The Demorest has a needle hole that is noticeably offset, the "unknown" has the needle hole centered with the presser bar hole. I have several for White - and all of them have the set screw hole to the side, not the back.