Thread is read only, therefore starting another one for MCB1000 HID and Binary Files...
\Keil\Arm\Bin\ELFDWT.exe will exactly do that - create the checksum and put it into the given .axf file:
C:\Keil\arm\bin\ElfDwt abc.axf C:\Keil\Arm\bin\ElfDwt abc.axf BIN(abc.bin)
The first example creates the checksum and 'patches' file abc.axf. The second example does the same and additionally creates a .bin file where the checksum is patched as well. This can be used for loading via mass storage device.
The ElfDWT.exe utility is part of the recent MDK.