BSP using RFC connection

Is there a option on the BSP application 'system' HTML page login.htm to select a R/3 system you want to RFC to ? For example I've created a BSP application which references the system login page and I need the option to select a destination R/3 system. Note I've already set-up the RFC connections via SM59 all I need to do now is build the functionality in the login.htm for RFC selection. Does SAP have a solution for such a scenario or do you have to custom build this ? Any suggestions would be appreciated.