Found the following problems:
RFspatialGridDataFrame-class.Rd:26:1: Warning: nested emphasis <code>
installed size is  7.8Mb
  sub-directories of 1Mb or more:
    R      1.6Mb
    help   1.2Mb
    libs   4.8Mb
installed size is  8.1Mb
  sub-directories of 1Mb or more:
    R      2.0Mb
    help   1.2Mb
    libs   4.7Mb
installed size is  7.4Mb
  sub-directories of 1Mb or more:
    R      1.6Mb
    help   1.2Mb
    libs   4.5Mb
installed size is  8.2Mb
  sub-directories of 1Mb or more:
    R      2.1Mb
    help   1.2Mb
    libs   4.8Mb
installed size is  7.4Mb
  sub-directories of 1Mb or more:
    R      1.6Mb
    help   1.2Mb
    libs   4.5Mb
installed size is  6.1Mb
  sub-directories of 1Mb or more:
    R      1.6Mb
    help   1.2Mb
    libs   3.1Mb