Hello,
For low citations, try to find some good reasons. This really depends on your background, the research field etc. For example, if your research is the engineering field, you could argue that that the number of citations are typically low. If you work in the industry, try to show that you work has been adopted in the product line, standardization bodies, etc., bringing in significant benefits to your company and society as a whole, etc. If your research is basic science, then you could argue that your work is published in journals with very high impact factor etc. Years after publication may also be relevant. Or you may have provided a comprehensive solution to a long standing classical problem. Getting a few more reference letters from outside US may be advisable.
I think the office wants to know of your reputation in your filed of expertise. Any additional evidence that could support this would be useful in your RFE.
Good luck.