Hi Nalini,
There can be a way out using custom PCRs incorporated inside the benefits processing sub-schema ( UDD0 / ur client's custom copied from UDD0).
The base of calculation is generally /102 ( 401K ) and /115 ( bonus ).
The limit amount can be calculated with the required % and stored in a custom W/T ( say 9XXX) in var table.
In the next PCR you can set up a test condition that will enquire if the combined amount of the ER match is greater than 9XXX.
Then based on that condition you can decide whether to send 9XXX ( when combined ER % exceeds limit ) to RT or the individual ER contributions ( when combined ER % doesn't exceed limit ) to RT.
Regards
JP