Unless you have an electorate wide multi-member electorate (not as common as proportional systems rare) you will require geographic electoral boundaries to be

Unless you have an electorate wide multi-member electorate (not as common as proportional systems rare) you will require geographic electoral boundaries to be drawn. The UK’s AV referendum was not for proportional representation but instant runoff voting for single member electorates. Which is a better system but in the UK in 2011 clearly would benefit the Lib Dems much more than actual multi member electorates would.