A method for performing wireless communication by a first device and an apparatus supporting the same are proposed. For example, the first device may obtain information related to a sidelink (SL) positioning reference signal (PRS) configuration. For example, the first device may trigger resource selection in slot n. For example, the first device may perform sensing within a sensing window. For example, the first device may determine a selection window. For example, the first device may determine one or more candidate resources within the selection window. For example, the one or more candidate resources may be in one or more candidate slots within the selection window, and may include the one or more REs. For example, the first device may select a first SL PRS resource from among the one or more candidate resources. For example, the first device may transmit a first SL PRS based on the first SL PRS resource.