  RhPb was initially recognized as one of a CoSn-like compounds with $P6/mmm$
symmetry, containing an ideal kagome lattice of $d$-block atoms. However,
theoretical calculations predict the realization of the phonon soft mode which
leads to the kagome lattice distortion and stabilization of the structure with
$P\bar{6}2m$ symmetry [A. Ptok et al., Phys. Rev. B 104, 054305 (2021)]. Here,
we present the single crystal x-ray diffraction results supporting this
prediction. Furthermore, we discuss the main dynamical properties of RhPb with
$P\bar{6}2m$ symmetry. The bulk phononic dispersion curves contain several
flattened bands, Dirac nodal lines, and triple degenerate Dirac points. As a
consequence, the phononic drumhead surface state is realized for the (100)
surface, terminated by the zigzag-like edge of Pb honeycomb sublattice.
