Yes, you can apply RTI to obtain Copies of your Answer Sheets from Kerala Public Service Commission (KPSC).
KPSC is a body created by the Constitution of India and advises the Government on all matters relating to Civil Services referred to it under Article 320 (3) of the Constitution of India. KPSC is a "Public Authority" as per Section 2 (h) of the RTI Act 2005 and falls under its ambit.
You can file RTI to obtain Certified Copies of your Answer / OMR Sheets under Section 2 (j) of the RTI Act from KPSC by addressing the same to the designated "Public Information Officer (PIO)" through Registered Post and by paying the prescribed fee. You should attach a Copy of your Admit Card and mention your Roll No., Registration No., Name of the Exam clearly in the Application.
To know more about the procedure to file RTI Applications for Answer / OMR Sheets, please refer https://onlinerti.com/how-to-file-rti-online-for-exam
To know more about the procedure to file RTI Applications, please refer https://onlinerti.com/