I am devlopeing some application wherein i have to store the keys in secure manner and do some cryptographic operation on it.
You can't use it directly. You need to develop (or buy) a trusted application and then have your app talk to it through the secure API it provides. This may or may not be usable on all devices, so unless you control the device and/or firmware, it is not guaranteed that you can use it all.
The system keystore on some devices already uses hardware-backed storage for RSA keys (Nexus 7 for example), but it is not standard and some devices only have a software implementation.