As our docs say, th ejob version is a bit different. Please note the extra "name" parameter required for it to work!
"curl" -i -X POST -H "Content-Type: multipart/form-data" -H "x-api-key: <Your API>" -F "a=upload" -F "filename=@[output_filepath]" -F "name=[output_filepath]" "http://<Your IP>:3344/printer/job/<Your Printer Name>"