  Motivated by recent interest in collectivity in small systems, we calculate
the harmonic flow response to initial geometry deformations within weakly
coupled QCD kinetic theory using the first correction to the free-streaming
background. We derive a parametric scaling formula that relates harmonic flow
in systems of different sizes and different generic initial gluon
distributions. We comment on similarities and differences between the full QCD
effective kinetic theory and the toy models used previously. Finally we
calculate the centrality dependence of the integrated elliptic flow $v_2$ in
oxygen-oxygen, proton-lead and proton-proton collision systems.
