If you are a developer, add the report in page actions (in page designer go to View-> Page actions) by customizing the Role center page. It is same as how customizing a normal page.
Another way, the user can add their desired report in his role center. After opening RTC page, goto the report where it is tagged, and choose the report and right click and select the option 'Add to Reports on Role center ribbon. It will affect only for that user.
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Another way, the user can add their desired report in his role center. After opening RTC page, goto the report where it is tagged, and choose the report and right click and select the option 'Add to Reports on Role center ribbon. It will affect only for that user.