  The interaction of a charged particle with its own field results in the
"self-force" on the particle, which includes but is more general than the
radiation reaction force. In the vicinity of the particle in curved spacetime,
one may follow Dirac and split the retarded field of the particle into two
parts, (1) the singular source field, ~q/r, and (2) the regular remainder
field. The singular source field exerts no force on the particle, and the
self-force is entirely caused by the regular remainder. We describe an
elementary multipole decomposition of the singular source field which allows
for the calculation of the self-force on a scalar-charged particle orbiting a
Schwarzschild black hole.
