addWMSLegend(map, uri, position = "topright", layerId = NULL)

leaflet(
  options = leafletOptions(
    center = c(-33.95293, 20.82824),
    zoom = 14,
    minZoom = 5,
    maxZoom = 18,
    maxBounds = list(
      c(-33.91444, 20.75351),
      c(-33.98731, 20.90626)
    )
  )
) %>%
  addWMSTiles(
    baseUrl = paste0(
      "http://maps.kartoza.com/web/?",
      "map=/web/Boosmansbos/Boosmansbos.qgs"
    ),
    layers = "Boosmansbos",
    options = WMSTileOptions(format = "image/png", transparent = TRUE),
    attribution = paste0(
      "(c)<a href= \"http://kartoza.com\">Kartoza.com</a> and ",
      "<a href= \"http://www.ngi.gov.za/\">SA-NGI</a>"
    )
  ) %>%
  addWMSLegend(
    uri = paste0(
      "http://maps.kartoza.com/web/?",
      "map=/web/Boosmansbos/Boosmansbos.qgs&&SERVICE=WMS&VERSION=1.3.0",
      "&SLD_VERSION=1.1.0&REQUEST=GetLegendGraphic&FORMAT=image/jpeg&LAYER=Boosmansbos&STYLE="
    )
  )