Keane played for Ireland between under-17 and under-19 level before making the switch to England's youth system
Asked if he knew where Rice was coming from over the difficulty of the decision, he said: "Yeah, definitely. I have some sympathy for him.
"It's not an easy decision, it wasn't for me at the time, so I can only imagine it's harder for him.
"I don't know what his family situation is, who's Irish or whatever, but I knew when I changed that I felt really, really English.
"My dad is Irish but I don't know any of his Irish family, so I've never really felt like I'm fully Irish.
"So, I don't know how Declan feels but that was part of my thinking behind my choice.
"But it's one of them things. He's made a decision, we're happy that he's here and hopefully now people can now just forget that and let him prove his talent on the football pitch."