A Rho Chi = "Rush Counselor". Essentially when a Rushee is going through Panhellenic Rush, the rushees must visit ALL of the houses on campus. All the rushees are divided into groups and visit the sororities on a rotational basis.

Each Rushee group has a Rho Chi (Rush Counsellor) and this is a sorority member on campus. The Rho Chi is the person to whom the rushees in that group should direct any questions which they may have. However, since the Rho Chi belongs to a sorority on campus, the sorority which they belong to is kept secret, so as to keep them "neutral" and "unbiased". So for the person asking you about the Kappa Delta member, this girl's identity was kept from the rushees to keep the rushees from being biased when signing their bid cards. Hope that this clarified it for you.