The 10¢ denomination was used to make up rates, so a single use on document is not likely. I also have a postal cancel of R734 on the last day of sale.
Just got done looking through a stack of about 40 documents with R733 and R734 used on them and virtually all are used in conjunction with documentary reds of the period, the majority the undated reds. The closest I've come to a solo usage is an attached pair on a stock certificate with no accompanying reds. One of the nicest examples (aesthetically at least) is an unpunched/unperfinned intact block of 4 on document.