The first step of peak detection in Skyline involves taking the second derivative of the chromatogram, and finding the places where that second derivative crosses the X-axis.

You can see what the second derivative looks like by right-clicking on the chromatogram in Skyline and choosing "Transform > Second Derivative".

I would recommend using Skyline-daily to look at the second derivative chromatogram instead of Skyline 22.2, because in older versions of Skyline you would not see the parts of the second derivative chromatogram that were below the X-axis.

After Skyline has found pairs of places where the second derivative crosses the X-axis Skyline does some more work to widen the peak boundaries so that the peak boundaries encompass all of what a human would consider to be the peak (I am a little unsure how the widening of the peak boundaries algorithm works).

There is a bit more information about peak finding in section 3.3 of Dr Pino's "Skyline ecosystem" paper:

https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/full/10.1002/mas.21540
-- Nick