Well, you can't get more RAM. RAM is a physical thing. But you can get more Virtual Memory by adding a swap area or swap file. My TF700T has 1GB and no swap enabled.
But I don't see why you would need to buy that Roehsoft product to enable swapping. The device is running a Linux kernel after all, and with all the facilities needed for using swap space, as far as I can tell. You would need a rooted device, and you would have to fiddle a bit with the system. Probably not too difficult, but the truth is - I don't want to even try it, because a micro SD card is terribly slow on a TF700, much slower than the already very slow eMMC. I can't imagine it would be worth the hassle. The device has a problem with slow eMMC, which results in the various slowdowns and hickups, and that's a problem that could be improved by adding a lot more RAM. But it will not help to simulate that by using microSD swap space, it can only make the problem worse.