Howdy!
I'm sorry but answer is NO... :( You cannot add SSD in addition to your stock HDD because ASUS Q552UB has only one internal Serial ATA interface. In case that you will need SSD instead of your stock HDD, you have to replace it by appropriate 2,5" Serial ATA SSD drive.
If you need to connect additional storage, it must be connected via external USB 3.0 port (transfer rate 5Gbps) so I suggest to use some small factor USB 3.0 flash drive like Samsung 128GB USB 3.0 Flash Drive Duo (MUF-128CB/AM) - see on Amazon: [http://a.co/1ZmmJ2a|http://a.co/1ZmmJ2a]