Download Calendar (iCal), decompress it, and put it in the Docklets folder of RocketDock (Windows (C :) → Program Files (x86) → RocketDock).

Right-click the place you want to create, and click "iCal" from "Add Item".

The characters are out of alignment.

Right-click the icon and click "Icon Settings".

Correct the month shift, set the day size, etc., and click OK.

This is completed,

I changed to this one because I made an icon with the display of the month.

Although the month display overlaps, it will be raised so that it cannot be seen.

Done.