I had forgotten about that project. I also thought it was inactive. :'(
Looking at the contents of the rpm the executable appears to be /usr/bin/vdkb You shouldn't need to type the full path.
You can get a list of all the files an rpm installs with these commands.
If the rpm has not been installed:
rpm -qpl vdkbuilder-1.2.5-1.i386.rpm | less
If the rpm is already installed:
rpm -ql vdkbuilder | less
Piping the output through "less" allows you to scroll through the contents when they need more then one screen to display. Use the up/down arrow keys, page up/page dn to scroll. Press q to exit "less". Piping the contents through "less" isn't necessary if the contents on the rpm will fit on one screen.