MDF Window Sil Gap

[bezzas7]

Hello All,

One of the interior window sil's is MDF (don't ask).

Problem is there is a slight gap between where the sil butts up against the uPVC window frame.

I have tried filling the gap with caulk and filler but it just shrinks and cracks.

could i use Ronseal High Performance Wood Filler to fill the gap between the sil and the uPVC window frame?

Google "ronseal.co.uk/products/high-performance-wood-filler"

will it stick to the frame?

Thanks

Andy