Few queries here.
1) How thick is the wall?
2) What will be the loading of the RSJ?
3) What does the lintel support?
4) What is the span, and size of the lintel?

I'd be rather concerned at supporting an RSJ on a single brick wall without
a pillar and a concrete load spreading pad. Maybe the answer to the lintel
support problem is to replace the lintel with a piece of angle iron, which
would enable the rsj to be fitted above it.
Regards
Capitol