RFC Destination with SAProuterString

Hi guys,

i would like to have a connection to a 3rd party system of a client of ours to send an IDoc from sender system into XI.

Therefore i think i have everything done in the SLD.

I am now stuck at the RFC-Destination from XI-System to 3rd party system. Unfortunately we have to use a SAProuter-String - but i have no clue how:

I confinfigured as follows:

Connectiontype: 3

target host: i put the destination IP of teh 3rd party system

gateway host: do i have to put the SAProuter-string here

gateway-service: do i need it

sorry for my question but i already tried everything.