RNAView release version 2.0.0 supports mmCIF file input, yielding results identical to PDB file input.
The program input/output is otherwise as described in Yang, H., Jossinet, F., Leontis, N., Chen, L., Westbrook, J., Berman, H.M., Westhof, E. (2003). Tools for the automatic identification and classification of RNA base pairs. Nucleic Acids Research 31.13: 3450-3460, https://doi.org/10.1093/nar/gkg529