Observing frequency of waveform in LTspice
Double click on the part of the circuit you want to measure and a waveform window should pop up (when the simulation is running) and your waveform you want to measure will show. Either adjust the runtime of the simulation or zoom in on the waveform so you can actually see the entire waveform cycles. Then click on part of the cycle and drag your mouse the the exact same point to the next cycle - the bottom of the waveform window will show the frequency of the distance between these two points.


Click on image and you will see what I mean.