  We explain the application of a recently developed analytic continuation
method to extract the electromagnetic transition form factors for the nucleon
resonances ($N^*$) within a dynamical coupled-channel model of meson-baryon
reactions.Illustrative results of the obtained $N^*\rightarrow \gamma N$
transition form factors, defined at the resonance pole positions on the complex
energy plane, for the well isolated $P_{33}$ and $D_{13}$, and the complicated
$P_{11}$ resonances are presented. A formula has been developed to give an
unified representation of the effects due to the first two $P_{11}$ poles,
which are near the $\pi\Delta$ threshold, but are on different Riemann sheets.
We also find that a simple formula, with its parameters determined in the
Laurent expansions of $\pi N \rightarrow \pi N$ and $\gamma N \rightarrow\pi N$
amplitudes, can reproduce to a very large extent the exact solutions of the
considered model at energies near the real parts of the extracted resonance
positions. We indicate the differences between our results and those extracted
from the approaches using the Breit-Wigner parametrization of resonant
amplitudes to fit the data.
