Circular 0031/2011 - available here - recommends TextASub as an effective means of sourcing fully-qualified primary teachers for substitute vacancies in your school.
To advertise for a substitute teacher you will need to agree to the following disclaimer:
I understand that TextaSub is not a recruitment facility. It is an advertising service which IPPN provides to facilitate the short-term recruitment of fully qualified, Teaching Council-registered primary school teachers. It is to be used for substitute vacancies of 24 weeks or less c.f. Governance Manual for Primary Schools 2015 – 2019 (Appendix D, Section 3.2).
I understand that IPPN and TextaSub are not responsible for the integrity of data provided by personnel registered with this service.
understand that it is our (the school/employer) responsibility to
verify the identity, qualifications and suitability of substitute
teachers. In any case where there is doubt, substitute teachers must
be required to provide the necessary evidence (1-6 below) for
verification and suitability checking.