This is a continuation of the old and now locked thread: http://www.keil.com/forum/59594/
Before spending a full day with Google, it might have been a good thing to spend a couple of minutes on the Keil site.
This page seems to indicate limited simulation support for STM32F103RB: http://www.keil.com/dd/chip/4231.htm
So Google might not have many solutions available except the more traditional route of getting a debugger probe and real hardware.