Yes, you can add the yad repo, and no, you can't add the refracta repo, because there isn't one. Here's the entry for yad from sources.list in the jessie-sysv build. The gpg command for adding the key is in the comments. If you prefer to use the apt command for adding a key, that'll work, too. (I don't remember it.)
- Code:
# Yad
deb http://debs.slavino.sk/ testing main non-free
# deb-src http://debs.slavino.sk/ testing main
## gpg --recv-keys FFF06A93
## gpg --export --armor FFF06A93 | apt-key add -
Note: You may want to remove that when jessie goes stable, in case newer versions of yad don't work with it.