RLF at 5 GHz of the selected BL Lac candidates (black histogram). The gray histogram shows the effects of including the five objects located in the wedge. The results from Padovani et al. (2007) are in red, while blue dots refer to the work by Marchã & Caccianiga (2013) for classical BL Lacs. We also report (as plus signs) three points at low luminosity of the Marchã & Caccianiga RLF for Type 0 AGNs. The green line is the RLF normalized to match the number of objects of our sample with log P_r> 23.8 [W Hz^-1], after having adopted the same slope of Marchã & Caccianiga (2013).