Uma Samhita cf. Valmiki Ramayana

[Govind Kashyap]

Pranaam to all vidwans,

I am unable to find the text named "Uma Samhita" which supposedly talks about the greatness of, and gives the recitation procedures of, the Valmiki Ramayana.  

This Uma Samhita is said to be a section of the Vayu Purana, but from what I could check, there is no such section in the Vayu Purana.

Again, there is a section named Uma Samhita in the Shiva Purana, but this Uma Samhita has different contents.

I would be much obliged if I could be get any guidance/direction in this matter.

with thanks

GK