As per reports, actor Aamir Khan is set to rap for a song that will be used for promoting his upcoming film 'Dangal'. The song is said to be composed by Pritam with lyrics by Amitabh Bhattacharya. While Aamir made his singing debut with the track 'Ae Kya Bolti Tu', he also sang for the 2007 film 'Taare Zameen Par'.