Methods, systems, and devices for wireless communications are described. Some wireless communications systems may support the transmission of a scheduling request via a physical sidelink feedback channel (PSFCH). In some cases, a user equipment (UE) may determine a configuration of a set of PSFCH resource blocks (RBs). The UE may receive a first bit map that may indicate a subset of the set of PSFCH RBs allocated for transmitting a scheduling request on the PSFCH, and the UE may receive a second bit map that may indicate a second subset of the PSFCH RBs allocated for hybrid automatic repeat request (HARQ) messages. The UE may transmit a scheduling request via one or more RBs of the first subset of the PSFCH RBs. In some cases, the UE may generate a waveform for transmitting the scheduling request message, and the waveform may be based on the number of RBs selected.