Thanks for the reply.
How do you access the hard drive with riscos? Is it possible to send a app
to the hard disk?
If you have a Raspberry Pi with the RISC OS RC12a SD card image on the SD card then you will see that application directories (those that begin with a '!') are included inside the directories 'Apps' and 'Diversions'. If you plug in a USB pen drive (for simplicity no larger than 2Gbytes) you will see another disc icon on the icon bar that is a SCSIFS drive. Click over it to open it and then you can simply drag and drop any apps you want to from the SDFS drive to the SCSIFS drive. Simples.
You can also use !Store to download any apps you want onto the hard disc and open the archive to put them where you want.
What you mean by 'the hard disc' is, of course, unclear - the SD card or the pen drive or a 'USB hard drive' plugged into a USB socket?