RSAGA is no longer under active development and no support is available. Try Rsagacmd.
Latest RSAGA version with support for SAGA GIS 2.3 LTS - 7.0.0
Provides access to geocomputing and terrain analysis functions of the geographical information system (GIS) ‘SAGA’ (System for Automated Geoscientific Analyses) from within R by running the command line version of SAGA. This package furthermore provides several R functions for handling ASCII grids, including a flexible framework for applying local functions (including predict methods of fitted models) and focal functions to multiple grids. SAGA GIS is available under GPLv2 / LGPLv2 licence from http://sourceforge.net/projects/saga-gis/.
You can install RSAGA 1.3.0 from CRAN with:
install.packages("RSAGA", dependencies = TRUE)
Or you can get the latest version from GitHub with:
devtools::install_github("r-spatial/RSAGA", dependencies = TRUE)