This had been long ago discussed in this problem whether it is to be traced to Valmikiramayana and there were split opinions among traditionalists maintaining it should be there in Valmiki Ramayana, while in any of the published editions it was not trace.
Here is a link to the problem:
found on the net. Now, about Hanumannataka, it has got many many verses from the popular Rama plays, from Mahanataka of Bhavabhuti, Anargharaghava of Murari and Balaramayana of Rajashekhara as have noticed many. It is the same with another small छायानाटक aslo compiled with verses from many other popular plays. There has been opinion that this हनुमन्नाटक also could have been a छाया नाटक considering its structure distinct from the normal plays and probably of its extended version beyond the maximum Anka-s, 10 to15 in different versions, it got the name महानाटक.
Hope the verse would be traced to Ramayana this time at last.