Is it possible to make vertical slides with keynote? Can they be turned around? I'm trying to make a slideshow for an installation using monitors placed vertically.... but I'm not sure if that's possible. Thank you for your help!
You can specify a custom size for your slides by going to Document in the top right corner, it wil open a box on the right side of your screen and there wil be an entry regarding the size of your slides, the default is 1024 x 768.
Open this selector and you see "custom size".
If you enter 768 x 1024 in the resulting window the slides wil be in a vertical orientation.
ps. my keynote version is 6.2 and it is in dutch so I don't know what the menu items will be called in your version