Thanks for your input. A check of the Kingston website just made the problem worse. The memory identified as being compatible has a part number that is completely different than the number shown on the Kingston memory that was sold with the PC. A search of the web showed that the memory was a Samsung model, not Kingston. Assuming that both companies have a workable memory for this PC, nothing exist to indicate that it's OK to install memories from different companies together into any PC. A check of the Toshiba website for support seems to be nonexistent. All I found was their vague .pdf listing the PC's specifications. I could not find anything about the memory makers name or part number.
In addition the websites indicates that the Pc's maximum memory capacity is 16 gb. They don't actually say that its a max of 16 gb per PC or each slot. All other sources seem to state that it may not be possible to use a 8 GB to a 4 GB memory, thus you can only have a PC with two 4 GB memories, likewise with two 8 GB memory. The Kingston had suggested another memory, but it was discontinued. It's numbers did not match the memory already in the PC. I have to wonder if it's possible to find any memory to add to the second slot.