Using experimental data for magnetic hyperfine fields obtained through the technique of time differential perturbed γ–γ angular correlations (TDPAC) in the highly diluted system CeR (R=Gd, Tb), we theoretically discuss the formation of the local moments at the Ce impurity site, adopting an intermediate valence model. The ferromagnetic rare-earth host is considered as a transition metal in the beginning of a 5d series and the CeR alloys are described as strongly d–f correlated and hybridized systems. One calculates the hyperfine field which reproduces quite well the experimental data. The Ce valence in these systems is also obtained, giving values in good agreement with experimental results and theoretical claims involving Gd and Tb band calculations. Some comments about the diluted systems YbR (R=Gd, Tb) are also made.