If you want to make your dmg the minimum size you need to look all the way down to the bottom of the "Size" drop-down, click on "Custom", and change 100 MB to 10 MB in the pop-up; you should then see another pop-up that tells you that 10.5 MB is the minimum size. Click on "OK", and you're good to go. (Edit: You can, of course, specify any custom size in between.)
If you eject the disk image (Edit: Control-click on it to see the option, or click on the "Eject" icon in a Finder window.) and then double-click on the dmg, Keychain Access should enter your password and auto-open it, which will cause the disk image to reappear, and you can drag your private folder into it.
Bear in mind, though, that storing your password in KA (may) negate(s) your having password-protected the folder in the first place, because anybody with access to your Mac may be able to/can double-click on the dmg and open it.
Against that possibility I've got two dmgs with passwords stored in MY memory only.
Note: There's another option you can use if you expect your private file to grow continuously; post back if you'd like to go that route.
Last edited by artie505; 12/03/15 10:48 PM. Reason: Clarify +
