Cills for Rationel windows

[Becca]

 

Hoping for some help on cills for Rationel windows.  The Rationel cills, supplied by ADW in Scotland (which apparently they get from MSP Scotland, mentioned on the forums) are pressed aluminium, but we hoped to specify shaped profile "extruded" cills, like these, as shared by @Moonshine:

 

 

Our construction will be blocks and render as an outer leaf to the timber frame. We didn't want any concrete cills, so they would sit on top of the blocks.  I thought the extruded type would be better than pressed metal in this context.  More stable and easier to make watertight.

 

Has anyone found a supplier for these cills, as MSP Scotland can't do these, just the pressed type.  And has anyone used them with Rationel windows?  

 

If we do have to go the pressed route, it will need to be a non-standard order to MSP Scotland, as we need more of depth than ADW/Rationel provide on their cill drawings, from what our timber frame company are showing me.

 

Thanks ?