Speaking from a Dublin experience, the Community Welfare Officer in your local health centre is the person who looks afer rent allowance. It is the job of the tenant to find a property then apply to the CWO for rent allowance and they inspect the property to make sure it is of good standard and worth the rental asking price.
You can try advertising in the local paper and stating that you will take rent allowance, or put up notices on local boards/websites. Some CWO's will take note if you have a rent allowance property if it is in their area, so worth finding out who they are and making contact.
Hope this helps
Cara Mc K.