@Cactus225
1) you will have to fill up the anexture-1A along with the Undertaking certificate, in which you will have to mention your existing RTR(C) number.
2) with the number 1 you send them a DD of 5000 ( eligible to get for 20 years ) and surrender the existing original RTR(C)
3)i would suggest u to send them a print out of your admit card showing your roll number and a center plus a copy of result sheet in which your name is showing along with the attested copy of your UK RT.
you should be good to go with this....