Nicholas,
As Jim said better not to use RFC_READ_TABLE because it is not released for Customer usage.It could be due to large amount of data.If in D and Q itself if you are facing problems with this FM then just imagine what will be the case in Production where it is bound to process huge no.of data.
Better go through SAP Service Market Place search for RFC_READ_TABLE.You will be getting more info on the usage of this FM and its pros and cons.
K.Kiran.