FAQ: Can I use a different RNase A with the Monarch® Genomic DNA Purification Kit? 

As long as the RNase A has a similar concentration and activity specifications, it should be OK to use. However, many RNase A products do not have the same quality specifications as Monarch RNase A, which has no detectable endonuclease, exonuclease, DNase and protease activity and is free of DNA. These specifications may be relevant for your downstream applications.