KDE theme manager in pure OpenBox WM

I've setup a pure OpenBox system with no specific desktop environment like Gnome, KDE, or Xfce, etc… It works well, and I have been able to customise the desktop's appearance with software like ObConf (for OpenBox themes) and LXAppearance (for GTK themes). However, I have recently installed DigiKam which is a KDE application, and its GUI does not follow what I've setup for OpenBox and GTK.

Question: How can I customise the theme in Digikam (and other KDE apps that I might use) in my system? Is there a standalone equivalent to ObConf and LXAppearance for KDE? Or is there another way to do it? Thanks.