As @jelo.
And your first and second mistakes are
The exit link I was given for terminate is
dkr1.ssisurveys.com/projects/end?rst=2&psidTerminate
1. there is no equal sign between the parameter name "psid" and the value
2. The value "Terminate" is obviously wrong. Here you usually return the id that was added to the link by the panel company
You see, "rst" seems to be the result of this respondent ("complete", "screenout", "quota full")
and in "psid" the panel company wants to know which one of its members completed the questionnaire and whom they hav to pay.
And as you use "panel integration" you defined a question where you store this parameter and just add it to the end url.
As jelo already mentioned, "PASSTHRU" is not used, and in my opinion is outdated since there is "panel integration".
Joffm