[Elecraft] spectrogram question

[Andrew Moore]

I used Spectrogram to set up my K2's filters.  When lining up the
frequency peak with the marker for my preferred sidetone (650 Hz in my
case), the typical display shows the usual bandwidth shape, plus a
relatively sharp (and very narrow bandwidth) spike slightly offset from
the center of the overall filter bandwidth.  Something like this:

http://www.photogs.org/filters.jpg

Do I aim for putting the marker on the sharp peak (slightly offset from
center), or the approximate center of the wider bandwidth shape?

--Andrew, NV1B