Currently bookmarks do not support options for SSH. It's important to add since it's not always possible to add entries in ~/.ssh/config. For example, when we have cloud instances (eg AWS) the public IP might change or a domain name might not be available etc. Especially for the AWS instances where we have randomly generated SSH keys, it's important to have the option to use the identity file with a bookmark.
Confirmed on konsole from git master, the bookmark doesn't keep the -i input.