Being a student in a European country, I sometimes pray with our sunni brothers in their mosques since I do not find mosques of the followers of Ahl al Bayt (as) here.
Sunni point their index fingers of the right hand while they are doing the qad’ah and the greetings (in the sujud).
I would like to know if this act is obligate, haram or if their is any recommandation about doing this since I never learnt about this with shia.

No this is neither part of the tashahud, nor a recommended act.