How to: New order Binance API via RStudio

I am trying to create a new order via the Binance API using RStudio.

I found the Binance Official API Docs and figured out that I should use
POST /api/v3/order (HMAC SHA256).

The following script doesn't work out for me:

< url='https://api.binance.com/api/v3/order'

< POST(url,
add_headers("X-MBX-APIKEY"= [my API key]),
query=list("symbol"="ETHBTC",
"side"="BUY",
"type"="MARKET",
"quantity"=1,
recvWindow=5000,
"timestamp"=1499827319559,
"signature"=???),
verbose())

Does anyone know what I'm doing wrong and how I can create an order via the Binance API using RSTUDIO and how I can create my signature?