Is it possible to restore a backup from a single disk on RAID1?
I believe it can be done but you lose the recovery partition and depending on your IT skills and willingness to start from scratch if the O/S gets hosed it might be a viable opportunity.

Note that I have not done this with Mavericks or Time Machine.

You need to boot from an O/S install disk. you can make one out of an 8GB flash drive with the Mavericks installer app and a number of freely available tools. Once you have booted from the O/S installer flash drive, bring up disk utility and wipe the drives of all partitions. Delete them. Then under the RAID tab make a RAID out of those two disks and partition as you want. Probably just best to stick with one partition unless you have a specific need for more than one.

Once that is done you can install the o/s on the RAID and restore your apps/files/settings from the external disk.

Note that I restored with a disk image using Carbon Copy Cloner from within disk utility, worked great but on an earlier O/S. So feedback from other folks would be good before committing to this procedure.