Rename this yellow folder to a Mac-specific folder.

Download and unzip ico.

Right-click the folder you want to change and click Properties.

Here, the folder name is “1”.

1's properties open.

Click “Customize”.

Click Change Icon.

Click “Browse”.

Select Folder.ico of the downloaded ico.

Click “OK”.

Click OK again.

The folder of 1 has been changed.

Same for 2 to 5.

Restart RocketDock and it's done.

Change the desktop icons as well.

「Change desktop icon」 is done by right-clicking the taskbar and selecting 「Taskbar settings」→ 「Personal settings」→ 「Themes」→ 「Desktop icon settings」.

Select PC and click "Change Icon".

This time, I changed it to Macintosh HD, just like I changed the folder icon.

Change the name of the icon and position it to the upper right to complete.