The RCM6710 and RCM6760 have the transformer and Ethernet jack, but the RCM6700 and RCM6750 do not.
As you can see from the schematic, those modules put TX+/TX- and RX+/RX- on the header. What signals does the switch chip expect?
And the schematic for the development board shows taking those signals directly into an Ethernet jack with integrated magnetics:
To disable auto MDIX, it looks like you can define DMAETH100_PXDR_AMDIX_EN as 0 in your project macros.