Hi there.
XVKBD by default does not comes with .desktop file.
Open text editor, paste this into it:
[Desktop Entry]
Exec=xvkbd
Icon=/usr/share/icons/oxygen/64x64/devices/input-keyboard.png
Type=Application
Terminal=false
Name=XVKbd
Save it as:
~/.local/share/applications/xvkbd.desktop
You can now find it in the K-Menu.
Cheers.
Andrzej