Joe Patrick writes

I was wondering that when the Prepay Oyster Cards come in will they
put in readers (like ones Between the Chiltern & Tube Platforms)
between Amersham & Harrow at DLR Stations

That would be the logical solution - in much the same way that DLR used
ticket validators when it originally opened. IIRC it's also effectively
what will happen at any ungated LU station, or a station where the gates
will be left open for parts of the day.

or would they be paid for when the PSA scans it.

I doubt it.

--
Dave