Perspective login without keyboard?

I don’t. I am using a hope industrial touchscreen, which as far as I know only emulates a mouse.

I have found the solution to my issue. Perhaps it can help someone else. The elo touch driver that hope industrial posts on their website, only provides mouse emulation. Windows doesn’t recognize this as a touchscreen. I went to the elo website and downloaded the newest driver and replaced the one from hope, and then the OSK began working as expected.