  The recent discovery of AV$_3$Sb$_5$ (A=K,Rb,Cs) has uncovered an intriguing
arena for exotic Fermi surface instabilities in a kagome metal. Among them,
superconductivity is found in the vicinity of multiple van Hove singularities,
exhibiting indications of unconventional pairing. We show that the sublattice
interference mechanism is central to understanding the formation of
superconductivity in a kagome metal. Starting from an appropriately chosen
minimal tight-binding model with multiple with multiple van Hove singularities
close to the Fermi level for AV$_3$Sb$_5$, we provide a random phase
approximation analysis of superconducting instabilities. Non-local Coulomb
repulsion, the sublattice profile of the van Hove bands, and the bare
interaction strength turn out to be the crucial parameters to determine the
preferred pairing symmetry. Implications for potentially topological surface
states are discussed, along with a proposal for additional measurements to pin
down the nature of superconductivity in AV$_3$Sb$_5$.
