adding memory to dell optiplex 3040 SFF

I bought new memory for this computer... Kingston KCP3L16ND8/8 8gb 1600mhz Low Voltage Mod Mem which is supposed to be DDR3L-1600 UDIMM, but I only see one slot that looks like a memory slot in this box.... and the stick is too long for the slot.  Am I supposed to be looking somewhere else (like under something) for it?  Is this the wrong memory?  The Kingston memory finder said this was the memory for this system. I have 8gb and it is supposed to be expandable to 16.