When you dismiss him, he will go to wherever you initially found him, or the Lucky 38 Suite if the player has unlocked it. If you told the Dead Horses and Sorrows to evacuate Zion, regardless of how you completed Civilised Man's Burden, he will be found in the Bitter Springs Refugee Camp.
If you told Follows-Chalk to stay in Zion or did not complete Civilized Man's Burden, and then drove out the White-Legs, he will be found in the Dead Horses Camp. If you told Follows-Chalk to go see civilisation during Civilized Man's Burden and then chose drive the White-Legs out of Zion, he will be found in Freeside.
Follows-Chalk may end up in a variety of locations depending on some choices you made during Honest Hearts. This mod re-introduces Follows-Chalk into the game as a permanent follower in the most immersive and seamless way possible.