Unfortunately InstallShield LE doesn't ship with Microsoft Report Viewer 2012. If you could locate a prq from another source you could add the appropriate .prq file to the prerequisites directory which should cause it to show up in ISLE (that default location is C:\Program Files (x86)\InstallShield\2013LE\SetupPrerequisites). It is worth noting that InstallShield Professional and Premier editions come with the prerequisite editor which allows you to create your own prereqs.
Another option you may wish to consider with ISLE is to create an install condition that looks for Microsoft Report Viewer 2012. You can use this functionality to prevent the install from continuing if Report Viewer isn't on the machine. In the requirements section under section 5, you'll see a list of System Software requirements you can check. To create your own, right-click System Software requirements and select Create New Launch Condition (System Search Wizard). Follow the prompts in the wizard to create your condition.
