Depending on the employer and position that you applied for, the results of your reference check may or may not be kept confidential.
If the initial invitation email you received from Checkster says that the feedback will be kept confidential, then the employer will not be able to see each rater's responses individually. In this case the reference report is presented to the employer in an aggregated format (in a series of charts and graphs) along with the answers of all of the other raters, and each rater's responses cannot be traced back to them. Additionally, the employer will only be able to view the report after at least 2-3 raters have responded, in order to ensure confidentiality of the feedback.
If the initial invitation email you received from the employer doesn't mention that the feedback will be kept confidential, then it's likely that the employer will be able to see each rater's responses individually, in a non-aggregated, non-confidential format.