Some people put their left hand on their forehead and recite ayat ul-Kursi. Is it permissible?

Yes, I noticed this. After prayers, I was wondering what they were doing. I did not know that it was ayat ul-Kursi. You know some people come usually from Pakistan and India, after the prayer first thing they do is holding their head. I think everybody has a headache. After the prayer all of sudden their hand is on their head. Left hand on forehead and reciting ayat ul-Kursi three times, this is not from the sunnah.[1]

Reference:

[1] http://islamqa.info/en/162985