  An integral for a scalar function with respect to a multimeasure $N$ taking
its values in a locally convex space is introduced. The definition is
independent of the selections of $N$ and is related to a functional version of
the Bartle-Dunford-Schwartz integral with respect to a vector measure presented
by Lewis. Its properties are studied together with its application to
Radon-Nikodym theorems in order to represent as an integrable derivative the
ratio of two general multimeasures or two $d_H$-multimeasures; equivalent
conditions are provided in both cases.
