I would like to rename some fields in my attribute table:
XRF_N3in something else. It seems quite a easy issue but I don't find any information about how can I do that... I've QGIS 1.8 in Mac Mountain Lion.
Since 2.16, you can edit field names in the layer properties when editing is enabled:
Renaming is possible using Table Manager plugin (http://plugins.qgis.org/plugins/tablemanager/)