Krushna,
Are you able to connect to the RDS DB remotely via JDBC? In theory you should be able to per Amazon's documentation:
Adding an Amazon RDS DB Instance to Your Java Application Environment - AWS Elastic Beanstalk
So you'd need to open Subset on your current TDM server and setup the connection profile to point to the RDS DB. Obviously your TDM server will need access to the RDS server which can be complicated if the TDM server in on your corporate network without any sort of link to RDS. Opening DB ports for RDS to the internet as a whole is a bad idea...
If you were attempting to mask locally via FDM for example - that would require an AWS instance since RDS doesn't provide you with any local java access to the DB server.