You can use this URL with a POST method as described here.
POST: Creates a KPI in a test run.
|name||string||The name of the new KPI.|
|operand||string||The operand to use for the new KPI. Possible values are “<=” and “>=”.|
|target||number||The target value of the new KPI.|
|category||string||The category of the new KPI.|
|statType||string||The statistic type of the new KPI.|
|chartAxisSeriesType||string||The series type of the new KPI.|
|summaryStatType||string||The summary statistic type of the new KPI.|
|bucketCount||number||The number of buckets to use when calculating the data. By default it will use the default number of buckets, which is usually 100.|
|measurementName||string||The measurement name for the new KPI. (Only required if category is "System Under Test" or "Measurements".)|
|series||list of strings||The series against which the KPI will be applied.|
|KPI||string||The URL of the newly created KPI.|
"name": "Max transaction rate should be greater than 10",
"Max transaction rate should be greater than 10": "http://localhost:5000/analyzer/api/1.0/Workspace%201/Project%201/Series%201/Test%201/1/kpis/Max%20transaction%20rate%20should%20be%20greater%20than%2010"