The RF100A form, used to declare non-use period of a car, is usually located at:

https://www.motortax.ie/OMT/pdf/RF100A_en.pdf

I've added a copy to Google Docs.

https://docs.google.com/open?id=1DsJLxKSCb1Og2wSidG0k_2_YRTHSSLrjshSg6t8Of_QRUp6EzoDB_sVs3Xsf