Marketo API documentation states “The programName and lookupField parameters are required, and the source and reason parameters are optional. The resulting activity will be attributed to the corresponding named program. The source and reason parameters are arbitrary string fields which can be added to the request to embed those values in the resulting activities. These may be used as constraints in the corresponding triggers and filters.”
how do i determine the values for these fields?
Looks like the Push Lead API (though I agree that should have been provided in the post).
programName is, exactly as it states, the name of the program in Marketo.
lookupField is the REST API name of the field you wish to dedupe on, with the same rules as the Sync Lead API but also supporting the special field mktToken (which is unlikely to be of use to you).