מסכּים זײַן

Etymology
Literally, "to be in agreement".

Verb

 * 1) to agree

Usage notes
Like all periphrastic verbs with זײַן, its past tense is formed with האָבן, and not זײַן.

As such, איך האָב מסכּים געווען is the correct past tense and not איך בין מסכּים געווען.