It was shown by E. Witten \ref[J. High Energy Phys. <strong>1998</strong>, no. 12, Paper 19, 41 pp. (electronic); <A HREF="/msnmain?fn=105&fmt=doc&r=1&pg1=CNO&s1=1674715&loc=fromrevtext">MR1674715 (2000e:81151)</A>] that the D-brane charge in type IIB string theory over a space-time $M$ should be regarded as an element of a twisted $K$-theory group $K_[H](M)$, where $H$ is a global $3$-form associated to the $B$-field. Furthermore, in \ref[P. Bouwknegt et al., Comm. Math. Phys. <strong> 228</strong> (2002), no. 1, 17--45; <A HREF="/msnmain?fn=105&fmt=doc&r=1&pg1=CNO&s1=1911247&loc=fromrevtext">MR1911247 (2003g:58049)</A>], the authors and their collaborators provided a way to interpret the twisted $K$-theory within the category of bundle gerbes and stable isomorphisms. The paper under review discusses in detail the Chern-Weil term associated to the $K$-theoretic bundle gerbe, extending the construction of \ref[P. Bouwknegt et al., op. cit.] to the equivariant and holomorphic cases.