RTI Second Appeal through legal practitioner.

There is no need for an advocate to file second appeal. Party in person too can file 2nd appeal. If you could not get any result from 1st appeal then you can file for 2nd appeal and then at the time of hearing if you wish you want to engage any advocate then the advocate will file his vakalatnama to plead on your behalf before the concerned authority.

If you insist on filing the second appeal through RTI act through a lawyer, you may contact an advocate with the knowledge on the subject matter,  to file the second appeal