  Be stars are found to rotate close to their critical rotation and therefore
they are considered as an important laboratory of study for stellar rotation.
In this context, we obtain the projected rotational velocity of a sample of
classical Be Southern stars in the BeSOS database via Fourier Transform in an
automated way for several absorption lines at different epochs. A Gaussian
profile is fitted to eight observed photospheric HeI lines in order to select
automatically the spectral signal given by areas under the curve of 95.45%,
98.75% and 99.83% from the profile to obtain $v \sin i$ via Fourier Transform
technique. The values obtained are in global agreement with the literature.
Analysing only one line is not enough to set the $v \sin i$ value, depending on
the line the value in most cases are underestimated with respect to
$\lambda$4471. When gravity darkening effects are including, apparent values
increases by $\sim10$%. The resolution of the instrument PUCHEROS used for
BeSOS spectra ($R \sim 17\,000$) constrain a theoretical lower bound possible
at $v \sin i \sim 100$ km s$^{-1}$. The procedure has limitations using a
linear limb-darkening function with $\varepsilon = 0.6$ for classical Be stars
rotating close to the break-up velocity without gravity-darkening corrections,
which can't be negligible. Previous works measure $v \ sin i$ values using just
one spectral line and here we demonstrate that with more lines the results can
varies. This could be due to the photospheric distribution of atomic
transitions on classical Be stars.
