You must use an ER ESD with the 'Indirect Reference' bit set to trigger the building of a linkage descriptor for the target symbol. Set the 'executable' attribute to 'code' and the scope to Import-Export.

An RLD entry whose target (R Pointer) is an ESD with the 'Indirect Reference' bit set resolves to the linkage descriptor. An RLD entry whose target is an ER ESD without the 'Indirect Reference' bit set resolves directly to the referenced symbol.