How can I sort RArray in descending order ?

How can I sort RArray in descending order ?

class TSample
{
public:
TBuf8<20> Name;
TInt Marks;
};

RArray sampleArray(8,_FOFF(TSample,Marks));

// Now Assume some data added to the samleArray

sampleArray.SortSigned();

Is it possible to sort samplearray in descending order by SortSigned function() ?

I know this may be possible by
sampleArray.Sort(TLinearOrder< T > anOrder);