I suspect that my child may have rls

Rule out underlying. If you think your child has RLS (actually more common than you think), you probably have - this is genetic in many cases. Ask child to describe and of note, symptoms will only be in evening at rest as opposed to some "other diagnoses" like growing pains or musculoskeletal issues. See physician to rule out underlying medical issues or medications that are causing and then try the behavioral treat.
"need to move" Many children have a need to move. This is most common during the day, but can also occur at night. Restless legs syndrome (rls) is not used for children. Most are labeled as adhd. Significant movement may occur during sleep including walking around the house. This is a normal variant. Suppression of movement during rem sleep does not develop until adulthood.