"Reconciling your roster" means to ensure that everyone who has been attending your class and is expecting to get credit for taking the class appears on your iSIS class roster.
The easiest way to reconcile your roster is to print your class roster from within iSIS and compare that to your attendance or your K-State Online roster.
At the last day of class each semester, the iSIS team creates the Grade Rosters for the bulk of the classes for that semester. These rosters are generated based on the enrollments at the time of their creation. If someone should have been enrolled in the class, but did not, then they will not appear in the grade roster and, hence, will not receive a grade in the class.
The student must officially enroll in the class to be listed on the grade roster. The student should begin the late enrollment process in their deans office.