Atom lasers based on rf-outcoupling can be described by a set of coupled ge
neralized Gross-Pitaevskii equations (GPE). We compare the theoretical pred
ictions obtained by numerically integrating the time-dependent GPE of an ef
fective one-dimensional model with recently measured experimental data for
the F = 2 and F = 1 states of Rb-87. We conclude that the output of a rf at
om-laser can be described by this model in a satisfactory way.