Hi Christine
We are not using RTI in IC yet - but do intend to start with it for next year.
However, I did attend a training on this module a few years ago, and recently set up a test environment for RTI on our staging server (for the purpose of demonstration to others in my district). So I may be able to help you out with some of the places in IC that you need to look for various things.
As far as I recall from the training - System Admin stuff exists in two places: The obvious one is Index > System Admin > Response to Intervention, and the less obvious place is under: Index > System Admin > Custom > Attribute/Dictionary > Plan. This second place is where you can create Universal Screeners that may be selectable within an RTI plan.
You also need to do a bunch of user access control (to set the right people up with the appropriate rights), but some of that is done when you by create "teams" (per RIT student, which are very similar to SpEd teams).
User with access to a students RTI plan, can then see that students' RTI tabs under Index > Student Info > Response to Intervention > General/Caseload. This is where teams are set up, and meetings can be tracked, and documents can be created etc... You can also score progress toward a goal - but the RTI plan needs to be locked for that to work (which is a mistake I made).