Hi @ishwarlal ,
Thank you so much for your interest in our products and for using our community.
Regarding your question, I checked the Kinetis MCU reference manual.
Taking the K20P64M72SF1RM as an example, as you mentioned, it specifies the Kinetis series for the device.

However, in the IMXRT1060RM and IMXRT1064RM, there are no such registers to specify the RT series of the device.
I will escalate your issue to the relevant internal teams at NXP.
Wish it helps you.
If you still have question about it, please kindly let me know.
Wish you a nice day!
Best Regards
MayLiu