The material color makes it hard to see the flaking. Here is a couple more showing the cross section, edge sharpness, and flaking. I believe the rough white stone to be a layer of limestone inclusion, not a removed cortex as it goes throughout the piece and is present on the other side.
Limestone is too brittle and prone to breaking to be used for this type of application. It would not hold a cutting edge very long or maybe not at all when put to use as a knife.
I'll try to explain why I don't think what you're seeing is knapping. In pic1, side-A to the left, that edge is where a chip came off (note the visible cracks and steps on side-B). That edge is just where a flake detached along those small jagged cracks and steps, followed the weakest path and took some of the cortex with it. It was not made by percussion nor pressure flaking (re-touching) to make a tool from the flake IMO.
That's about as good as I can do. Let's hear from someone else that believes they understand what they're looking at.