I have a T100-CHI and the keyboard never appeared in "Other Device" list. I finally chose the "+ Add Bluetooth or other device" option at the top. The dialog box box "Add a device" appeared so I selected the first option "Bluetooth". Nothing showed up so I held the bluetooth switch (upper left) on the keyboard to the far right until the keyboard appeared. When it appeared I let go of the switch and selected the keyboard in the list. A dialog box appeared with "Enter the PIN for Asus T100CHI DOCKING". Of course I didn't know the pin so using the onscreen keyboard I typed in my own eight digit key "12345678" and selected connect. I quickly entered the eight digit key in the keyboard and pressed Enter. I had to do follow this same sequence a number of times before I managed to get the timing right but don't give up.
Good luck!