My textbook has stressed that 7ths in supertonic and subdominant chords need to be prepared and resolved in the same voice. I am trying to do this in the following progression but since my IV7 doesnt go to a V chord and the ^2 is in the bass of the following chord I guess it doesnt resolve then at all? Is this correct? I suppose I could double the root of ii7 to resolve the 7th of IV7 but is this necessary?
Yes, classic voice leading would have that B in bar 1 fall to A in bar 2. You can double the root of the Am7 chord, but it really needs the 3rd, C. If anything is to be omitted, it's the 5th, E.
But - and we've been here before - the 'rules' are about SATB writing. You insist on slipping into 'keyboard style'. This is going to make it very hard for you to follow the rules of a SATB Chorale setting in the style of Bach.
This kind of question is tricky, because you start out with a fairly straight forward point - prepare and resolve sevenths in the same voice - but then complicate the situation by putting that specific question into a particular setting of your creation that seems to force all the other parts to do something disregarding the starting point about handling sevenths!
I look at it like this, The starting point up to the preparation and playing of the seventh, and then the bare minimum of what they should happen is this...
...personally I think it's helpful to take such questions and simplify things to figure out what the "normal" progression might be, things like reduce harmony to just triads, or just three parts, etc. In this case I want to see what it would be if the progression just continued sequentially in descending fifths...
...maybe something like that. I just want to see how the
A3 would be harmonized, and in that particular progression it's the chordal third of
viiø7, the doubled
A3 is degree
^2, so that seems OK.
But your progression goes not to
vii but to
ii. You could fulfill both the resolution of the seventh and keep your chosen root of
ii in this way...
The interesting thing is that the root progression doesn't change. If you weren't being strict about voice leading and seventh resolution, you could say this sounds just find. That just brings us back around to what the main objective is: harmonize a fixed bass part with seventh chords, or are we trying to handle the preparation and resolution of sevenths?
If it's the latter, change the bass.