This will be for my common bathroom installation as in the picture attached

Need to hunt around for something similar 16A  10mA model.

Where are you located?
Shopee got 10ma RCD
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M using ABB 10ma 25A RCD for the 10mA leakage protection coupled with B16 MCB for the overload protection at 16A.
The RCD is not meant for overload protection - for that you need a MCB. In other words you cannot have the RCD as standalone.
This setup consumes 3 slots in the DIN rail.

RCBOs combine this into one package (leakage protection + overload protection) into one slot single unit but it costs more.

[attachmentid=10426835]

At full load max heat (3300W heater) it consumes 13.77A, just under the 16A capacity of the MCB (86%).
Cable is 2.5mm stiff wire installed by developer + 50cm short length of flexible 3 core Fajar Cable installed by me.

Do note that you might need to use a bigger MCB if you have a >3.3kW heater (nowadays seems like quite a lot of 3.6 / 4.8kW models)