please use a commandblock with the following command

/setblock ~ ~ ~-1 wall_sign 1 replace {Text1:"{color:red,text:\"click\",extra:[{text:\" to respawn\",clickEvent:{action:run_command,value:\"/kill @p\"}}]}"}

or

/setblock ~ ~1 ~ standing_sign 1 replace {Text1:"{text:\"test\",extra:[{text:\" message\",clickEvent:{action:run_command,value:\"/say test\"}}]}"}

Both wont work due to an annoying bug that won't allow any players, OP or not OP, to run commands on signs.

Works with this command:

/setblock ~ ~ ~-1 standing_sign 0 replace {Text1:"{color:red,text:'click to respawn',clickEvent:{action:run_command,value:'/kill @p'}}

The problem lays at the escaping char \
it does work with ' not with \"

This is not intended behaviour, neither a duplicate.
Still a concern in the latest snapshot, please fix.

WARNING/NOTE/README:
Is the same as MC-62833 which has been incorrectly flagged as duplicate of MC-62255 which describes a total different point of the sign commands.