library(RCurl)

options(RCurlOptions = list(
  cainfo = system.file("CurlSSL", "cacert.pem", package = "RCurl"),
  followlocation = TRUE,
  httpheader = c(
    Accept = "text/xml",
    Accept = "multipart/*",'Content-Type' = "text/xml; charset=utf-8",
    SOAPAction="INTRANET URL"
  ),
  userpwd = "USERID:PASSWORD",
  netrc = TRUE,
  timeout = 100,
  postfields = CONTAINS SOAP DATA,
  writefunction = reader$update,
  verbose=  TRUE,
  httpauth = AUTH_BASIC)
)

getForm(
  uri = "INTRANET URL",
  file = fileUpload(
    filename = "C:\Users\Username\Desktop\image001.pdf",
    contentType = "application/pdf"
  ),
  upload=TRUE
)