  We consider the Boussinesq equation on the line for a broad class of Schwartz
initial data relevant for water waves. In a recent work, we identified ten main
sectors describing the asymptotic behavior of the solution, and for each of
these sectors we gave an exact expression for the leading asymptotic term in
the case when no solitons are present. In this paper, we derive an asymptotic
formula in Sector IV, characterized by $\frac{x}{t}\in (\frac{1}{\sqrt{3}},1)$,
in the case when solitons are present. In particular, our results provide an
exact expression for the soliton-radiation interaction to leading order and a
verification of the soliton resolution conjecture for the Boussinesq equation
in Sector IV.
