Let $\mathfrak{X}$ be an admissible formal scheme over $K^{\circ}$ of dimension $n+1$ with boundaryless generic fibre $\mathfrak{X}^{\textup{an}}$ and $L_{0},...,L_{n}$ line bundles on $\mathfrak{X}^{\textup{an}}$ endowed with formal metrics corresponding to the models $\mathfrak{L}_{0},...,\mathfrak{L}_{n}$ on $\mathfrak{X}$. Suppose that $L_{0}=L_{1}=\mathcal{O}_{\mathfrak{X}^{\textup{an}}}$, denote by $\|\cdot\|_{0}$ and $\|\cdot\|_{1}$ the metrics on $L_{0}$ respectively $L_{1}$ and set $f_{0}:=-\log\|1\|_{0}$, $f_{1}:=-\log\|1\|_{1}$. Suppose that $f_{0}$ and $f_{1}$ have compact support. Then