Currently there doesn't seem to be a way to specify both the role name and multiplicity for an association end.
One could, in theory, do something like this
Transaction "1 initiating" -> "* initiators" ActorRole
however this converts the "*" into a dot, plus the layout is really bad; in UML digrams one normally places the end name and the end multiplicity on different sides of the line.
Perhaps a new syntax could be introduced, e.g.
Transaction[1] "initiating" -> "initiators" ActorRole[*]
(where [1] would be optional/default).