As Kaushal has rightly said there are no special provisions for Presidents or Governors . Because RTI is meant for disclosure of virtually every information kept by any Public Authority provided this PA is not covered under Sec 24(second schedule) . There also discussions are on to remove DRDO for most of information kept by it.
There have been many instances of RTI applications being made to the President's Secretariat, including some high profile cases:
1. Exchange of letters between President Narayanan and PM Vajpayee
2. Disclosure of letters of support given by UPA allies to Congress
at the time of formation of the present Government
3. How many cars with red beacons does the President's Secretariat