How do I use rsync filters for backup?

[JoeS]

I'm trying to figure out how to use rsync and the filter rules to backup some of my directories. like /home and /etc.
I tried a test with a few of my home directories. I was trying to copy the health and knives directories with contents.

rsync -av --filter='merge /home/joe/filter-rule' documents/ test

I used this as filter-rule:
+ */
+ /knives
+ /health
- *

which is what I found in the man page, as well as looking on the net for articles. This copied all the directories from documents with nothing in them.
If I use +* for the first line it copies everything.
What am I missing; how do I just copy the directories and contents that I want.

Thanks

[JoeS]

I think I've found the answer. For filter rule file:

+ /health/***
+ /knives/***
- *