What exactly do you mean by "split my pension with my spouse"? A pension is paid to one person.
I assume that you are talking about your current spouse. If you are talking about having part of your pension paid to an ex-spouse, provide details and ignore the rest of this post.
Are you filing separately in a community property state? That's the only situation in which you might report part of your pension income as your spouse's income, if part or all of the pension is community income. Is that what you are asking about? We don't know anything about you or your tax situation except what you write in your post. We can't see your screen or your tax return.
Except for filing separately in a community property state, you can't split your pension income. If you and your spouse file a joint tax return, you report the total income that both of you received. The tax return doesn't show which one of you received the income. It just shows the total for the two of you together, so splitting income would have no effect. If you file separately you each have to report the income that each of you actually received individually. You can't report part of your income on your spouse's tax return.