System: The newcomer rolls Per+Enigmas difficulty 9, -1 per mark level (see below) if present. One success indicate to her that another Strider is in the near area ("near" for a Strider mean several square kilometers, depending of the terrain); two gives her the aproximate bearing; three the bearing and the distance; four the location of a 500 square meters area where the other Strider is; five the exact point. Residents of an area or that frequent the same spots usually leave some kind of secret mark, in the form of a grafitti, a landscape feature or even some architectural feature. Like a hieroglyphic, it will mean nothing to non-Striders (some grafitti are even at display in the NY MOMA museum) but its structure, size and colors will indicate to any tribemate the name and meeting points of the writer.
The level makes the mark more perceptible to other Garou, but also more obvious to anybody. A two level mark can attract the attention of other Garou, Gangrel leeches or Dreamspeaker mages, and a three level mark might be detected by werewolf hunters or human investigators. Nobody has ever heard of four level markings, but a secretive Strider should be in very dire circunstances to make such a risky move.
If there are no marks present, the gift manifests in a mystic way. The user just "knows" there is someone near, like in "Highlander" or almost any John Woo movie.