Your chromatogram seems to dip below zero, which often means that you are looking at the Savitzky-Golay smoothed chromatogram.
In order to see the chromatogram that Skyline was looking at when it figured out the height you should choose "View > Transform > Interpolated".

Here's a page which talks about how Skyline calculates background and height:
https://skyline.ms/wiki/home/software/Skyline/page.view?name=tip_peak_calc
-- Nick