When incarnating a Human, we use the head and hands tracker to compute the manikin position. Its working but it isn’t perfect. If you want a more accurate result, you can attach a bone to a Tracker.
First of all, the command take a bone as a parameter, you can choose which bone you want to attach in the custom parameter within the customization panel.
Make sure the tracker is powered and his position is currently tracked before loading your simulation.
Once Launched, you can choose which Tracker you want to Attach, by simply clicking on the tracker list.