The answer to your exact question is no; for income tax purposes you should not indicate that you are in the US Naval Reserve (i.e., a reservist). The ROTC, or Reserve Officers Training Corp, is in a different classification all its own. In fact, according to the Department of Defense, ROTC cadets are not considered active military (or inactive, or reserve) until after they
have completed their college program and taken an oath to either active duty, or at their
reserve / guard unit.
Obviously, however, your status and circumstances will change after graduation. However, for now, please do not indicate in TurboTax that you are in the military reserves.
It may additionally interest to know the following. ROTC Student Subsistence allowances, paid to ROTC
students participating in advanced training, are not considered taxable income, and thus don't need to be reported on any tax return. However, certain pay received during summer advanced camp, or similar, is
taxable.
Thank you for asking this important question, and good luck with your program of study.