  Materials with AV$_3$Sb$_5$ (A=K, Rb, Cs) stoichiometry are recently
discovered kagome superconductors with the electronic structure featuring a
Dirac band, van Hove singularities and flat bands. These systems undergo
anomalous charge-density-wave (CDW) transitions at $T_{\rm CDW}$~80-100 K,
resulting in the reconstruction of the Fermi surface from the pristine phase.
Although comprehensive investigations of the electronic structure via quantum
oscillations (QOs) have been performed on the sister compounds CsV$_3$Sb$_5$
and RbV$_3$Sb$_5$, a detailed QO study of KV$_3$Sb$_5$ is so far absent. Here,
we report the Shubnikov-de Haas QO study in KV$_3$Sb$_5$. We resolve a large
number of new frequencies with the highest frequency of 2202 T (occupying ~54%
of the Brillouin zone area in the $k_x$-$k_y$ plane). The Lifshitz-Kosevich
analysis further gives relatively small cyclotron effective masses, and the
angular dependence study reveals the two-dimensional nature of the frequencies
with a sufficient signal-to-noise ratio. Finally, we compare the QO spectra for
all three AV$_3$Sb$_5$ compounds collected under the same conditions, enabling
us to point out the similarities and differences across these systems. Our
results fill in the gap of the QO study in KV$_3$Sb$_5$ and provide valuable
data to understand the band structure of all three members of AV$_3$Sb$_5$.
